- Original Dungeons & Dragons had them as not-ugly, not-stupid giants in the Greyhawk supplement.
- Advanced Dungeons & Dragons had them in the Monster Manual, 17-22 hit dice and 7d6 points of damage on a normal attack, could cast any magic-user or cleric spells as if level 15, had eight psionic powers but were immune to psionic attack, and invisible at-will. They looked like beautiful 18-foot tall Greek giants. Levitate or ethereal twice a day.
- AD&D2 had them in the Monstrous Compendium #8, and they're basicaly buffed AD&D Titans. 20 hit dice, 7d6 damage from normal attack that they can do twice per round, can do a 10d6 special attack, can go etherial twice a day, casts spells as a level 20 wizard or cleric, has a grab-bag of utility powers like Levitate, Invisibility, Alter Self and Advanced Illusion usable at will once per round, and even can have a "thematically appropriate" special-snowflake power (given examples are creating water for sea-themed titan, removing all negative feelings such as hatred or depression for a love-themed titan and instakill for a death-themed titan).
- Dungeons & Dragons 3rd Edition had them in the Monster Manual as 25-foot perfect Greek-god humanoids with a dozen at-will arcane & divine spells as if level 20, and had a challenge rating of 21 (the Tarrasque is a 20). Levitate at-will, ethereal or gate twice a day.
- Dungeons & Dragons 4th Edition uses titans as giants that are more elemental-y and 3 levels higher than normal giants. And some how "necrotic" became an elemental thing. They're even uglier than giants, and these titans can't levitate. They were created by the Primordials for the sole purpose of wrecking everyone's shit, which is the only reason the Primordials ever created anything.
- Dungeons & Dragons 5th Edition doesn't have any specific lore for titans, but a few select creatures (As of the release of Ghosts of Saltmarsh, only 5) have the Titan tag. The only thing these creatures have in common seems to be that they are directly tied to the gods in some way: Empyreans, who are the children of gods, Astral Dreadnoughts, who were made by Dread Tharizdun, Atropals, who are stillborn gods, Krakens, who were created as living weapons by the gods, and finally the Tarrasque.