Finally I got this written, now see, what I was writing about the last few days: Roles!!!
In D&D 4e a lot of players were repulsed by the introduction of the class-roles, even though the books said, that they existed long ago and the classes were more built around those roles. Personally, I didn’t care about it, it just made party building that much easier. But since being classified as a role makes it much harder to actually visualize a different build, I thought: Let’s group any class into a group!
Here I will make a difference between combat-roles and outside-combat-roles, since every character should be able to participate in battle, while Social Interaction is often made by a single character. And I’ll dip into the archetypes a bit, without in-depth explanation, there are some builds out there, which makes it much clearer, if you prepare for a specific campaign.
Here the combat-roles:
Defenders are the typical front-liners, which can take punishment, are able to hold a line, protecting the backrow, and of course brings some punishment to the foes. In 4e he’s a very tactical role, in most previous editions, he is just swinging a weapon around hoping that his damage and presence is enough to fulfill that role.
Strikers are able to bring a humongeous amount of damage fast to the enemies. His main-role is to defeat the biggest threats as fast as possible or kill those off, which got some amount of damage from the Controller to lessen the numbers of enemies.
Leaders brings buffs for the party, leading how the battle will go on. AC-buffs for grindy battles, damage buffs for fast ones, the right buff at the same time is one of the most powerful thing. And of course he’s healing the party, ensuring their lifes while deciding effectively, who can participate how long in the thicks.
Controllers got are effects and strong debuffs. They often have damiging powers, which are able to get a lot of enemies in one sweep, they can change the battlefield to the party’s liking and make powerful foes to helpless ones (like stunning the same opponent consequently for 5 rounds).
No class is a pure build on these 4 basic roles and I chose the 4e terms, since Pen and Papers aren’t MMORPGs and therefore these roles have different ways and things to offer, than the correspondentive MMO-Role (Tank, Damage Per Second [DPS], Healer, Crowd Control)
Outside of Combat, these roles are more defining (not counting all possible, but those who I personally think are important):
Knowledge is power, and the Bookworm have all kind of knowledge skills paired with above average Intelligence (this is why they’re most often wizards), if the party needs more explanation, z
With a Brawn, you don’t have to worry about any physical challenge: Climbing a mountain path? No problem. Carrying the petrified Rogue out of the dungeon, while a cockatrice is at your heels? Piece of cake! Breaking a door? D’oh, rolled a 1!
Everyone who is a main-magic user is able to fulfill the Caster-role, when mundane tools ad tactics won’t work, just use a spell! There is treasure at the bottom of the lake and monsters which guard it? Water Breathing! We have to storm a fortress, overtaking the walls, fighting the guards and traps and get weakened to the final fight? Divination to find the treasure room, Dimension Door to shortcut! Some problems aren’t even remotely as easy to solve without a caster, like traveling to the City of Brass in the fire plane. To look for a portal which travels to it, getting to said portal while fighting off anything which is in the way or might think, that it’d be unwise to open a gate to the elemental fire? Annoying!
Without a Face, a person looks funny, a party looks poor. This is the guy who takes all the Charisma-based skills, to be able to smoothtalk, bluff or even force himself and his party members out of the most dangerous situation. A silvery tongue to a slippery guy. Or girl.
The Sneak(y Guy) is someone, is able to sneak ahead of the party for scouting, preparing ambushes or finding a way into a building (like climbing up the walls of a castle, take out the guard post and drop a rope for the rest). Sneaks and Spotters are natural enemies, even though a lot of Rangers fulfill both spots so well, that he should be his own archenemy.
Spotters are the ones who pumped everything in their Perception scores to be able to spot and search for everything. No enemy unseen, no treasure unfound, no DM slightly to really annoyed. There are reasons, why there is so many stealth options around.
Trappers are most often the Sneaky Guys as well and are responsible for traps and often locks as well. Since the Rogue (and later some rougish base classes) in 3e was the only one, who could find and disable magical traps, he was normally the trapper, in 4e and 5e everyone with an ability score to find traps (WIS or in 5e WIS or INT) and the right skill training/proficiencies can be a trapper now. Or leave the finding to the Spotter, even though it wouldn’t hurt to have him concentrate more on enemies.
Now that we know our roles, let’s see how our classes in 5e are to be categorized.
Barbarian
Combat-Role: The classic Barbarian is a more offensive, less defensive version of a Fighter and is therefore a Striker. Right? Actually, I think he shifted to be a Defender with a Striker secondary role. While Raging he can take a humongous deal of punishment to weapons, due his resistance to slashing, bludgeoning and piercing damage, as a Totem Warrior with the Totem Spirit of the Bear it extend to all damage except psychic and Danger Senses protects him even further. His Reckless Attack makes him a better target, provoking enemies to attack him rather his allies, Feral Instincts let him get a higher initiative, so he can better choose where to build up the front line. Most of his features makes him harder to kill or influence, better at being where he needs to be to protect others or helping out his allies or hindering his enemies, in both paths. On the Striker side he only get 2-3 attacks, a single reliable attack with advantage, a smallish bonus damage for Rages and a stronger Critical Hit, which only have a higher chance when using Reckless Attack. Enough Damage to be a threat to enemies, not enough to be an actual Striker, comparing with other classes.
Outside-Combat-Role: When there are no heads to smash, a Barbarian makes a wonderful Brawn, using his Rage feature to get Advantage on Strength rolls himself for a turn and much later Indomitable Might to always get high rolls. There is no special synergy with other roles, even though it’s common to let the strong guy make the intimidation with his muscle and charismatic Barbarians are always kinda neat and works well with the Berserker’s Intimidating Presence.

Bard
Combat-Role: As a class with good support, Bard’s were always the Leaders, even so their healing abilities came first at 3e pretty weak, in 4e stable and in 5e they’ve become main-casters with any vital healing and revive spell in their spell-list. The Bard’s features allows him to support his party in many ways, buffing them, removing mind-affecting affects and some other stuff. Due his Bard College and Magical Secret’s feature, he can easily fill some parts in other roles.
Outside-Combat-Role: Of course the Bard is your archetypical face, but he can get into other skill-depending roles due his skill-monkey features, so if you’re asking yourself, which ability to boost second after Charisma, you should consider which role outside of combat is still unfilled. Bard’s in the past were known for their aptitude in being the Bookworm, now there are less features for it, but the spell-list do have the vital divination spells. And as a main-caster he can fulfill the Caster role pretty well, having many diverse spells even outside combat and using spells from other classes as well.
So the Bard could fulfill any role quite easily.

Cleric
Combat-Role: If the Cleric wouldn’t be a Leader, no one would. He have the most healing and removing condition spells and a bunch of buffs. Depending on domain he could take any secondary role, even though it’s easiest to him to become a secondary Controller.
Outside-Combat-Role: Clerics are obviously Casters, even though they’re lacking the flexibility of a Wizard, they have other great spells, which makes a combination with a Wizard that much powerful. Since 5e doesn’t require the Cleric to have a high Charisma score, his Face value dropped as well, even though they’re still good as Bookworms, if INT wasn’t dumped. Since WIS is their main ability, clerics makes good Spotters, even though they can’t get proficiency with Perception on their own, so you have to get it otherwise. For most other roles they’re mediocre or just bad, depending on their armor.

Druid
Combat-Role: In one way or another the Druid was always stuck between being a Leader or a Controller, even though I’d put him in as a Controller, since his healing was lacking compared to a Cleric and his spells to control the battlefield and deal with multiple enemies are so great.
Outside-Combat-Role: Wild Shape makes the Druid the perfect Spotter and even as a Sneak, he can use this feature. No guard post will take any notice of a squirrel in a tree, as long they don’t have reasons to fear a Druid and even then it might be a ‘friend’ of said person and killing it would only summon the Druid’s wrath, right?
Druid’s get enough knowledge skills to stand in as a Bookworm and outside in nature he’s most likely the best Caster in the game. And Wild Shape can make him a decent Brawn at some point, in Circle of the Moon even a great one (a Rhinoceros certainly helps you with breaking doors).

Fighter
Combat-Role: As the archetypical Defender, the Fighter is supposed to have all the stuff you want a Defender to have. In pre-3e being at the front and hitting stuff was enough, in 3e he got Bonus Feats which could grant him special attacks without risk (like Disarming, Trip, etc. But hey, most spent them in Two-Weapon Fighting and ways to increase the damage) in 4e he got straight up powers to do his job. In 5e he get… the option to be a Defender. Unlike the Barbarian, who is a Defender at default, the Fighter do have the basics to be a Defender, but can easily be a Striker as well. For Defender take the Protection Fighting Style and the Battle Master archetype, for Striker the Champion archetype and any other Fighting Style (even though Defense won’t make you a better Striker). And the Eldritch Knight is a Striker with the ability to become a tertiary Controller. Pretty much Striker focused…
Outside-Combat-Role: Since old times a Fighter was always a Brawn, even though DEX-Fighters became popular in 3e and 5e makes it easier for them to survive without down-classing STR-Fighters too much. But after that, the Fighter do not have any special aptitude of being anything useful outside of combat, which means you have to choose your ability scores and background wisely, to be not a burden, when violence won’t help.

Monk
Combat-Role: Some might ask themselves, why Monks are in the first PHB, when this is so western heavy fantasy, but this goes some way back and the class is popular. I think because they’re deadly Strikers, which can deal a lot of attacks per turn, allowing them to hit the enemy almost every turn and when hitting is no concern, dealing a massive damage over time. Their features allows them to shake of effects which would hinder them, avoid damage if needed and to actually outrun foes, when they’re low on hit points. Since there is so much protection, he could stand in as a Defender as well, the Way of the Open Hand supports this, while Way of the Shadow makes him a more sneaky version of the Striker and Way of the Elements could bring him into either Defender or apprentice Controller direction.
Outside-Combat-Role: Monks are normally good Sneaks and Spotters, since their DEX and WIS is generally high and they have both proficiencies available. The Way of the Shadow brings a lot of Sneak options, which is great. In previous editions, they could be Brawns, too, but that will be now more the exception than the rule, since STR isn’t as necessary as before. The other roles don’t lie on the way of being a Monk.

Paladin
Combat-Role: Since old times, Paladins were the defenders of good, justice and the weak, so you should suggest, that they’re Defenders as a combat-role. Actually they’re more of Leaders, if we just take the Paladin’s features into account, Lay on Hands, a lot of supportive auras, etc. The real defending comes from the spells, especially those with Smite in their names, which can inflict several conditions depending on spell, which hinders the opponents to act as they want. And there is a lot of Striker potential, seeing how many ways the Paladin has to increase his damage, he’s able to real burn out a lot of resources to deal a humongous amount of damage, if he rolls critical, he could one-hit even a deadly foe. So it depends how you play if the Paladin will be more of a Striker, Leader or Defender. So I guess there will be a lot of Striker Paladins out there…
Outside-Combat-Role: If the Paladin is not a Face, nobody should. He use Charisma for his Paladin features, so it’d be higher than average, he got useful skills and from a role-play point of view, everybody with a pure heart should be friendly to a real Paladin. Most Rogues and other less morally inclined characters might have some problems here and there. As a secondary role, being a Brawn fits the classic Paladin, who wields a sword or a hammer as the main weapon, while wearing a shield.

Ranger
Combat-Role: Rangers were like highly specialized strikers in pre4e, since the Favored Enemy feature granted extra damage from the get-go, while in 4e they were definitely Strikers. Normally a Ranger was more like a warrior-type skill-monkey, a bit squishier than their Paladin and Fighter comrades, so they often stacked to ranged combat, which is a Striker part. And even in 5e, most combat-oriented features are more Striker focused, like a Striker oriented Fighting Style of choice, Foe Slayer or the subclasses, especially the hunter. The spells are some self-support to be more strikerly, a lot of utility and some group support. It’d be safe to say, that the Ranger is a Striker.
Outside-Combat-Role: The Ranger truly shines outside of combat as the most likely best single-classed Sneak, using three features which strengthens stealth (being stealthy while traveling at normal pace in your favored terrain, being able to get a +10 when lying in ambush and being able to hide as a bonus action), combining Ranger and Rogue might be a powerful option. Even as a Spotter he get some features, like Primeval Awareness and Feral Senses and as a Beat Master, he can have a great Spotter as a companion, so he don’t need to do it by his own. And he open up the tracking department, which isn’t an as important role, since most adventure’s will get you were you want, but open up new options. As a Bookworm, he’s more of a specialist for his Favored Enemies, using that feature to get advantage to the rolls.
Finally, since his spell-list is much about utility, he is a decent Caster in the wilds.

Rogue
Combat-Role: Striker. Sneak Attack, a lot of features to get out of trouble while providing no special support to other, no questions.
Outside-Combat-Role: Like Bards, Rogues have a lot of skill support, so he could be any role, except the Caster. If we pick the Roles he fulfills with the least effort, it’d be Trapper and Sneak, getting the first at the start and some supporting features like the Cunning action or the Thief subclass, even though an Arcane Trickster is even more potent, using magic to support this build while being able to even cast the Mage Hand spell stealthily.

Sorcerer
Combat-Role: This is a tricky one, in 3e the Sorcerer could be a real mean Controller, while the Striker role is also possible in 3e and the main focus in 4e. In 5e I’d stick to the Striker with the option to widens the area of effect to multiple enemies, taking care of some of the Controller’s tasks. Mainly because of the options of Metamagic, Twin Spells is a real mean thing, making it possible to leash at two opponents with strong spells, but the features also enhances his damage capabilities with some self-buff methods.
Outside-Combat-Role: Having a high Charisma score and at least some viable skill proficiencies, a Sorcerer is making a good Face, especially with some spells like Friends, Enchant Person and Disguise Self. His lack of spell-variety is making it hard to see him as a great Caster, especially since his spell-list is less about out of combat utility. The other roles aren’t fitting without some work.

Warlock
Combat-Role: The Warlock is trapped between being a Striker and Controller, because he can up his damage a bit by taking the Agonizing Blast Invocation and other Eldritch Blast enhancers, but most of his effects are more about debuffs and some battlefield control. So I’d personally see him as a mainly single-target Controller with Striker tendencies, since he has a lot of features, which are more Striker-like.
Outside-Combat-Role: The warlock can be a powerful Caster, using Rituals as main-focus and Invocations for some real utility outside combat and resetting spell slots due Pact Magic. Most of the Warlock’s features, Invocations and falls into the Caster department. After that, Face for high Charisma.

Wizard
Combat-Role: As you thought, having access to 7 subclasses and the broadest spell-list, the Wizard is pretty good at shifting his focus to be what the player want, but in the end, his spell-list is clearly that of a Controller, while having access to all kind of damaging spells, which enriches the Striker aspect. But that’d mean to leave out some of the best tactical advantages, a party can get at any time. And most Arcane Traditions are more about being a Controller.
Outside-Combat-Role: As an INT-based class, the Wizard is the archetypical Bookworm, who also can use his magic, to be even more knowledgeable. And nobody can be a better Caster than a Wizard, even though he lacks some stuff, the Cleric and Druid can do, but the Wizard has magical answers to almost every problem.

(OK, nowadays 1d6… they got too healthy!)
After reading this, you’ll see that most classes are what they’re promising, while some have potential or even main-builds which might be surprising. But