Muscle Wizard
Wizards use Intellect. Sorcerers use Charisma. Clerics use Wisdom. What about spellcasting based around other stats, like constitution or dexterity? How might they work?
What a horrible idea. Let's do it.
Psion
With 3rd Edition Psions, you could choose a stat to be your primary attribute. So, pick constitution, and be a metabolism psion. Pick Strength, and be FLEX MENTALLO, MAN OF MUSCLE MYSTERY
Wizard/Monk
D&D 3.5 core, with a few feats from Complete Warrior.
Level 20 (Wizard 5/ Monk 15), Goliath race.
Feats: Improved Natural Attack, ImpTWF, Double Hit, Deft Opportunist, Extend Spell, Combat Reflexes, etc.
Items: ask your DM if you can count Spiked Gauntlets as an Unarmed Attack (like brass knuckles) for Monk abilities
Damage: 5d6 +STR +whatever enhancement the gauntlets have. Increases to 6d6 +1d8 +STR +gauntlets with Enlarge Person. 5 attacks per round, or 7 with Flurry of Blows. Then add a Haste spell... jesus.
Cancer Mage
Like many bad ideas, we'll start with the Book of Vile Darkness.
There's a Prestige Class called Cancer Mage. The first level ability allows you to ignore any negative effects of a disease. In the same book there's a disease called Festering Anger, which makes your dick fall off and gives you 'roid rage, but grants a +2 to Strength, with an additional +2 per day.
Druid gets to cast Animal Companion as many times as they want before the game; let the Cancer Mage contract this disease years before the game.
How To Use Your Muscle
- The player race Illumian uses their strength bonus for additional spells per day, just as other races use intelligence or wisdom. You can FLEX your way to additional level nine spells.
- Take the "Improved Grappling" feat, for hundreds of lethal and nonlethal damage per round without provoking attacks of opportunity
- There's a feat that lets you intimidate creatures with low-to-no intelligence, and a feat that lets you add your Str bonus to Intimidate. So one might easily wrestle a Tarrasque non-lethally to 0HP, and then punch it until it gives you a piggyback ride.