Here is something I've just realized...
There are many ways to divide D&D classes into small groups; in D&D 2e, for example, you had Warriors (fighter, paladin and ranger), Wizards (Mage and Illusionist), Priests (Cleric and Druid) and Rogue (Thief and Bard).
It made plenty of sense to me at the time. In fact, I like a four-way division for all kinds of D&D (see here). My take on it would be something like warrior/wizard/leader/specialist. But that's the subject for another post.
D&D 5e has twelve classes: Barbarian, Bard, Cleric, Druid, Fighter, Monk, Paladin, Ranger, Rogue, Sorcerer, Warlock, Wizard.
The "groups" are not exactly clear-cut. There are plenty with sub-classes with spells, for example, and there is a "war cleric" that resembles a fighter (and even a "valor bard"), etc. However...
You can notice that five classes (Barbarian, Fighter, Monk, Paladin, Ranger) get a second attack at 5th level.
You could call these "warriors". Notice that they take different paths in other levels (the fighter gets a third attack at level 11, while the barbarian gets tougher, etc.).
Conversely, there are six classes (Cleric, Druid, Bard, Sorcerer, Warlock, Wizard) that get 3rd levels spells at 5th level. These are our "magic-users" (yes, I know that the Bard is a bit "hybrid").
In 5e, this is intentional; 3rd level spells (like fireball) represent a "jump" in power that is comparable with an extra attack (while the difference between 3rd and 4th level spells, for example, is not that significant).
And that leaves us with the rogue... that gets "uncanny dodge" ("Starting at 5th level, when an attacker that you can see hits you with an attack, you can use your reaction to halve the attack’s damage against you".), in addition to a few bonuses (sneak attack, proficiency bonus raise - which counts a bit more because of expertise, etc.)
|Art: Human/Shifter Rogue (detail) by Brandon Chang - source.|
The rogue is not a bad class in 5e, on the contrary; I've had several rogues in my games and they always worked well (unlike, maybe, warlocks and rangers).
But I've found this distinction curious. You could divided 11 classes between warriors and spell-casters, leaving the rogue as a (very important) odd duck.
This is probably a direction I'm pursuing in my minimalist 5e.