My current list of adventuring classes is:
Fighter - Characters for which mastery of weapons and combat (at all scales) is their defining archetype. My idea fighter encompasses also Knight, Samurai, Duelist, Warlord, Kensai, and perhaps surprisingly Monk.
Fanatic - Characters who mastery of combat comes from channeling emotion, passion, courage, faith and so forth rather than specifically from the mastery of arms. Barbarian as the raging primitive warrior cult berserker is one example out of many of possible Fanatic characters.
Rogue - Characters for which specialize in evasion, subterfuge and trickery and for which combat tends to be a secondary consideration.
Hunter - Combat focused characters where the focus is not on the weaponry but on the target of the attack. Instead of specializing in a weapon, they specialize in attacking a particular type of target. This class includes assassins, demon hunters, undead slayers, and anything else that specializes in taking down a particular type of foe. In my game, a "Ranger" as D&D tends to define the class are hunters that dip into other classes to gain magical abilities. An "Assassin" as D&D defines it is typically a multi-class hunter/rogue.
Paragon - Characters who embody the best traits of their race and who are naturally gifted. This class includes folk heroes and heroes who appear to overcome obstacles primarily by luck and verve rather than any sort of practiced skill.
Explorer - Characters who focus on successful movement as their defining attribute at both tactical and strategic scales. This is the class of getting from point A to point B successfully.
I also have an non-adventuring class that I've always wanted to make into an adventuring class but can't see a clear path to doing so:
Expert - This is the class of experts in all the things that are secondary to the rogue class and the true skill monkey class. This is the class of all the characters with superhuman skill at things other than combat, such as Detectives, Masters of Disguise, Gourmands, Savants, Prodigies, etc. I've never promoted this class to adventuring class because I can never actually balance them at high levels in combat situations. It's not obvious how they scale above 6th level or so.
Both Explorer and Hunter could be seen as "half classes" and blends of Fighter and Rogue focusing on different more limited aspects of those two classes portfolio but they still have their own siloed domain that neither Fighter nor Rogue have full access to. Both Hunter and Explorer natural dual class with Rogue and Fighter (and each other) quite well. Both Explorer and Paragon are jacks of all trades.
I then move into the magic using classes.
Wizard - These are characters that gain access to magic through mental discipline.
Cleric - These are characters that gain access to magic through devotion to a deity.
Sorcerer - These are characters that gain access to magic through esoteric birthright. In my game, this would include and cover all psionic type classes.
Shaman - These are characters that gain access to magic through bargains with spirits. In my game, Druid is just one narrow example of Shaman. An enormous amount of variation exists in the class, and pretty much every D&D spell using class ever conceived that isn't one of the prior three can be made using a Shaman. You want to play a Witch or Warlock, then you're a shaman.
Then there are the magic using half-casters.
Champion - These characters gain access to magic because they are chosen by deities to be their representatives on the earth embodying the deities favored virtues. Could be considered a half-class between Paragon and Cleric or perhaps Fighter and Cleric but has its own silo. Paladins are a narrow example of champions. In my game, literally hundreds of types of champions exist and can be built from the base class of which Paladin is just one variation.
Bard - Characters who have gained access to magic through ritual performance. A half-class of rogue and wizard or perhaps rogue and shaman, kept around for historic reasons and because there is enough of a silo that they can be defined as their own thing.
Feyborne - A sorcerer variation that could be considered a half-class of sorcerer and rogue. You gain access to magic because you are yourself a spiritual/magical being. In D&D terms, you don't gain spells; rather, you gain spell-like abilities. The most jack of all trades magic using class.
Everything is meant to be built by one of more of these classes. It's intended to be space spanning.