Murky is my favorite hero. He was my first purchase.
(Murky has super low hp, but if he dies, he only counts as a quarter of a kill for the other team. He also has an egg he can place on the map to re spawn from, and he'll always respawn from the egg in 6 seconds, no matter the normal death timer. So mostly he's annoying as all get out, and even when you kill him he's not worth much. But you can't ignore him either -- then he'll beat you with fish and slime until you die.)