If I'm being subjective, I'd say that the greatest hero in Sci Fi is Doctor Who. But if I'm being completely objective... I'd say it's Doctor Whom. ^*Edit: ^As ^a ^few ^have ^astutely ^pointed ^out, ^the ^character's ^name ^is ^just ^"The ^Doctor"; ^I ^should ^have ^said ^"the ^greatest ^sci ^fi ^show ^is ^Doctor ^Who" ^instead ^of ^"greatest ^hero ^in ^sci ^fi". ^Thankfully ^the ^dumb ^joke ^still ^works ^in ^that ^form.