Have we already forgotten The Family of Blood? Tsk.
The only thing I can remember right now is post-regeneration, he cut that Sycoraxian leaders arm off, then hit a switch to make him plunge hundreds of feet to the ground. That was pretty harsh of him! Didn't even check what was below, so for all we know that guy hit a baby.
That's what I was thinking; I think Tennant's Doctor did go that far?
Then, as that worked and scared the rest off, that laser weapon under London blew it up and he STILL got all high and mighty about it! I know he was still getting his head straight, and he was probably a bit miffed that it was genocide rather than him killing just one to scare off the rest, but he's still a big ol' murderer