I read a similar themed thread upon the old Outpost Gallifrey site and someone suggested Jonathan Harris as the first Doctor. Yeah, I know, "NO! NOT Dr. Smith!!!" Well certainly not what his character devolved into by the latter half of the first season onwards. But in the beginning, Smith was actually clever and calculating, willing to "dirty" his hands.
I think about the way Hartnell played the Doctor in the first three serials, right up to his "revelation" at the climax of "The Brink of Disaster". He was not a very likeable fellow. He kidnaps the teachers. He gets himself captured by the tribe of Gumm which leads to the others getting caught trying to rescue him. He intended to "brain" an injured caveman with a rock! In the Dalek serial, he fakes damage to the TARDIS just so he can explore the alien city. And while not directly his fault, the fact the Daleks take the fluid link complicates their crisis. And during "The Edge of Destruction", he accuses the teachers of sabotaging the craft. (Ahem, "Pot calling kettle...")
Don't these things seem like the schtick Dr. Smith would do? Before Smith devolved into a cringing coward, Harris did imbue Smith with a certain malevolent charm. Certainly he had a "seasoned" and expressive face that would have worked well for this mysterious stranger from another time.