Coolie (The Talons of Weng-Chiang)

A Chinese man was a member of the Tong of the Black Scorpion. He and other members were tasked with disposing of Buller's body. They were seen by the Fourth Doctor and Leela and fighting ensued. The gang were winning when a police whistle scared them away. Leela managed to detain this particular member of the group after the Doctor tripped him.

He was taken into custody by the police. Li H'sen Chang was asked to question him. While no one was looking, Chang slipped him a capsule of scorpion venom which he swallowed, killing him so that he would not talk. (TV: The Talons of Weng-Chiang)

Behind the scenes
In no way, shape or form is this character's in-universe name actually "coolie". It is the entire narrative point of his character that not even his name was revealed before he killed himself with poison. However, this distasteful and blatantly racist term was given in the credits, and so we still retain that in the title so that the article can be easily found from the search box.