I am going to go through all of the PHB core classes and see if I can give replacements:
- Bard - Warlord -- support through companion buffs, though would lack spells.
- Barbarian - Berserker -- c'mon, that is all it really is, right?
- Cleric - Priest -- just a name swap.
- Druid - Shaman -- to fill the niche of nature magic, even with some shapeshifting depending on whose mythology you go by.
- Fighter - Warrior -- just a name swap, seems more appropriate.
- Monk - Martial Artist -- just a name swap.
- Paladin - Knight -- like its counterpart but without the magic, has a set code of rules to live by, fights for a cause.
- Ranger - Scout -- has the flavor of watching for targets, watching over areas, can track, just lacks spells and favored enemies, can still have an animal companion.
- Rogue - Magician -- not to be confused with Magi who were wise and sometimes associated with the Priestly caste. This one practices magic, not real magic, but instead a sleight of hand deceitful hand is faster than the eye type of magic.
- Sorcerer - Elementalist -- blast 'em! Wreck 'em! Sabotage 'em! You know you play one of these just to blast away your enemies, don't lie. And Elementalist can do that with more efficiency! Charge up their powers using Meta Magic!
- Warlock - Witch -- replace the soul selling Warlock with a cauldron bubbling Witch! How do they get their powers? How does their magic operate? A good Warlock replacement!
- Wizard - Alchemist -- they can use recipes and their concoctions in place of spells in order to achieve similar effects.