He is best known for playing Strax, an occasional associate of the Doctor's. Besides appearing in episodes, Starkey also appears as Strax in a number of online promotional videos uploaded by the BBC under the title Strax Field Report and has also made public appearances in costume and in character as Strax at venues such as the Doctor Who Experience and the 2013 edition of Doctor Who at the Proms. In 2015, Starkey co-wrote the audio story Terror of the Sontarans with John Dorney. Outside of Doctor Who, starting from 2012, Starkey played the hobgoblin Randal Moon in Wizards vs Aliens.