Crazy Awesome: Garrus. Described via Word of God to be the unholy fusion of Jack Bauer and the Kool Aid Man. Even the Scrin describe him as insane.
To a lesser degree, Grenck the vorcha. Modified his translator to not only speak in something other than the You No Take Candle speech the vorcha usually have, he also has it speak in an English accent. He also wears a top hat and as the Scrin find out, is quite good with explosives.