6. He Made A Pair Of Guards Fall In An Acid Bath
It's not just the modern-era Doctors who've committed murder - the classic-era Doctors have jumped in on the bloodthirsty action, too.
In the Sixth Doctor serial Vengeance on Varos, the Doctor's body is taken away for disposal, after he is thought to have died. "Disposal" here means a melting-hot acid bath: it burns any flesh it comes into contact with, leaving its victims with no chance of survival.
Fortunately, the Doctor isn't dead, and he wakes up before his body can be properly disposed of. On the downside, there are two guards in the room with him, but wouldn't you know it, they're both stood right in front of the acid bath, with their backs to the Doctor. So you can probably guess what happens next.
Yep, that's right: they both end up getting dunked in the murder-juice. The Doctor startles the first guard by patting him on the back, which sends him tumbling into the acid, but the second guard puts up more of a fight: he and the Doctor have a bit of a tussle, before the guard's currently-burning friend gives him a quick tug and drags him into the bath too.
The Doctor could have just sneaked past these guards without them being aware of him, but instead, his actions resulted in two average grunts dying in an absolutely horrifying manner.