Breath of Fire

Breath of Fire is a series of RPGs developed by CAPCOM. The series all take place on the same dying world, but set hundreds of years appart, so that players can see how things get progressively worse. The player avatar is always Ryu (though he can be renamed), a dragon only just awakening to his powers. After adventuring through the world he'll usually have to fight God, or what passes for God in this world anyways.

Deis
Deis is a recurring sorceress in the BoF series, making apperances in each of the first three games. She's playable in the first two as well. Deis is a naga, a race closely tied to the dragons, which is why she's always around to help Ryu out. For some reason, possibly because her powers have been drained, she briefly appeared as human in Breath of Fire III. She is the syster of Myria.

Katt
Katt is a (of course) cat-girl and member of the party in BoF II. She's a strong physical fighter, though not as strong as Ryu, which she learns after picking a fight with him. She also doesn't wear any pants.

In her shaman form she abandons clothing altogether and ends up looking a bit more like a blue elf.

Myria
Myria is the would be saviour of the planet in Breath of Fire III. She has set herself up as god, and has decreed that the dragon race must be wiped out to save the planet. The player can agree, which abruptly ends the game, or disgree and fight her. For teh fight she transforms from her previous angelic body into a gigantic winged serpent. She presumibly dies after falling in combat as her space station burns up in the atmosphere.