I tend to have the wierdest nominations. And I can't think of too many now...anyways, let's begin:
1) HK-47 (Star Wars: KoTOR)
2) Agent 47 (Hitman)
3) The Spy (Team Fortress 2)
4) Deadpool (Marvel comics)
5) IG-88B (Star Wars)
6) James Bond
7) Sephiroth (FFVII)/Light Yagami (Death Note)
8) Asha (Iji)
9) Margaret Moonlight (No More Heroes)
10) Alice Moonlight (No More Heroes)
Sephiroth is technically an assassin, but he only pulled one act EVERYONE knows. Replacement is there if not legit.
--
WTH Duke; just, WTH