Baldurs Gate I & II both have characters with evil alignments in them. The best pure mage in both games is evil, and he has no issue with you being a back stabbing fucker. The first game has a larger selection of characters overall; the best cleric is evil, there is an ok evil fighter, and a decent evil thief. In the sequel there is also then a decent fighter who is evil, a few neutral characters (one of whom can be turned to evil), the same evil cleric who is still amazing, but most of the characters in the sequel are good. But as long as your reputation never drops below 3, no good character will leave the party.
KOTOR II is good for evil, as IIRC you can slowly convince most of the party members to the darkside, aside from one droid who is neutral (might be good, but he has a very small personality), two who are already evil (arguable), and two humans who are neutralish (both of whom could be argued as evil, but its complicated and D&D alignments are too constricting)
I haven't played much classic Fallout, but they do work for evil. IIRC you can do some fucked up stuff like making a party member who will die if he takes a certain drug take it just for a quick combat boost, you can child kill, you can slave, etc.
Thinking more, I don't remember much of the Two Neverwinter games, but I think Neverwinter 1 is mainly petty evil, whereas Neverwinter II (in its expansions at least) has more nuanced good / evil.
is a link to my personal list of FAQs. Please check there to see if it answers you question. This is still largely up to date, and I will try and remember to update it when I find the time.