- Bards without spells.
- Mesmerists (aka "Illusionists without spells")
- Alchemist/Witch (doesn't use the "X without spells" paradigm, just unlimited potion creation instead of memorization of spells.)
Some of these classes don't have any guaranteed magic; they have to negotiate with spirits or attempt to dominate humans or animals through force of will. They can do this at will, but this might not work. The few that can use spells (or potions) that always work must pay for that privilege; Necromancers can cast Cleric/M-U death-related spells, but only from scrolls, while Alchemists or Witches must brew their spells as potions.
And I thought: "Hmmm, it would be interesting to run a campaign or try a party that only used these classes, instead of standard Clerics or Magic-Users. And maybe no Fighters. Just Thieves and their variants (Miner, Smith, Leech, Apothecary.)"
Since almost all these classes can wear any armor and can fight equally well with whatever weapons they choose to start with, they aren't helpless, and they have equal combat ability. And since all the classes have very narrow abilities, a party composed entirely of these classes would spend most of the expedition doing tasks that any party member could do. The focus switches from class abilities to player cleverness.
I think it would be fun to try.