Conversation so far:
What roles did Danny DeVito play on television?
Danny Devito has played Louie de Palma on Taxi, SNL, Friends, and It's Always Sunny in Philadelphia
What was some voice over work that Danny DeVito has done?
Danny Devito has done voice work in My Little Pony: The Movie, The Earth Day Special, The Simpsons, Space Jam, and Hercules, The Lorax

Question: When did he start acting on television?
Self-contained rewrite: When did Danny DeVito start acting on television?