Ascaris was a minor, yet important villain in the Doctor Who story "The Romans". He was portrayed by Barry Jackson.
Ascaris was a Roman Legionary who was taken off duty by a centurion and told to assassinate a musician named Maximus Pettulian. A previous failure had caused the centurion to cut out his tongue, rendering him mute. He succeeded, stabbing Pettulian to death in the street, and a time traveller called the Doctor found Pettulian's body. After the centurion discovered him, the Doctor pretended to be Pettulian and was invited to the Roman camp.
The centurion was annoyed because he believed Ascaris had failed, but gave him a second chance by telling him to kill the Doctor. Ascaris entered the Doctor's room at night, armed with a dagger, but the Doctor attacked him. The Doctor's companion Vicki Pallister joined the fight and hit him with a vase, causing him to jump out of a window. In the novelisation, he was later demoted and forced to work on the construction team of Hadrian's Wall.