Becoming the Monster

[Biggus]

There are several other transformational prestige classes which change your type and/or give you a template, usually at 10th level. Acolyte of the Skin (CArc), Elemental Savant (CArc), Oozemaster (MotW), Verdant Lord (MotW), Green Star Adept (CArc), Alienist (CArc), Fang of Lolth (S&S) and probably a few more I've forgotten.

Note that Oozemaster, Verdant Lord and Fang of Lolth are all 3.0, and that Green Star Adept is widely regarded as one of the worst prestige classes in the whole of 3E.

Edit: quite a few more, it turns out: https://forums.giantitp.com/showthre...ange-your-Type