Evolving Mutant

[Gwazi Magnum]

Mainly out of curiousity can you all think of any kind of feats, classes/abilities in D&D that represents or could be used to represent a mutant of a character?
One that either made themselves that way or evolved that way?

Mainly I'm looking at the homebrew Evolutionist class here: http://www.giantitp.com/forums/showthread.php?240717-The-better-man-There-is-no-such-thing-base-class&p=13115715#post13115715

And wondering how close to it D&D can get to it without actually going Homebrew.

[Dr. Azkur]

Templating the heck out of it is what comes to mind first.

Savage Species has a few examples:
The Feral Creature template is this for creatures that, staying into the deep wild, needed to get more savage and physical.
Symbiotic Creature is an even better example, two creatures that found that symbiosis worked terrifically for them and eventually evolution brought them together (this happens a lot in animal planet).

[ShurikVch]

Some ideas:
Daelkyr Half Blood (http://eberronunlimited.wikidot.com/daelkyr-half-blood)
Flux Adept (http://dndtools.eu/classes/flux-adept/)
Geomancer (http://dndtools.eu/classes/geomancer/)

[Necroticplague]

Maybe some heavily refluffed incarnum could work?

That's freaking not how evolution worls, populations evolve, not indaviduals.

[lunar2]

abberant and abbysal heritor feats for inherited mutations. willing deformity for acquired mutations. also, grafts are nice.

[malonkey1]

If you're willing to use Pathfinder, you could do a lot with Synthesist Summoner.

[Fable Wright]

Maybe some heavily refluffed incarnum could work?
This. Totemist is pretty much the customizeable monster-in-a-can that can swap out abilities as the plot demands. It is the single closest class to Evolutionist in published material.

Also? A Daelkyr Half-Blood Totemist taking Aberration feats. It's a mutant attached to an evolving symbiote that grows new adaptations on a daily basis while slowly developing permanent useful traits. Surprisingly optimized to boot.

[Gwazi Magnum]

Interesting ideas.

Thanks for the help guys, I'll be sure to take a look into them.

[Dr. Azkur]

Oh! The Warshaper PrC might be of interest to you.

[Sheogoroth]

Another Pathfinder option, not so much a class, but the Mana Fever disease(which is relatively easy to acquire and leaves one's sanity mostly intact) does turn the afflicted into a hideous mutant.
http://www.d20pfsrd.com/bestiary/monster-listings/templates/mana-waste-mutant-cr-1