Conversation so far:
What work did he do on Doctor Who?
writing the second Doctor Who serial.
What contributions did he make?
The serial introduced the eponymous extraterrestrial villains that would quickly become the series' most popular and enduring monsters, and resulted in a major merchandising success for the BBC.

Question: What was the name of these villains?
Self-contained rewrite: What was the name of eponymous extraterrestrial villains?