XL5, a transparent robot invented by Professor Matic and Earth's most advanced mechanical man. Zoonie the Lazoon (voiced by David Graham): Venus' lazy, semi-telepathic pet from planet Colevio. During his early appearances, he can say no more than "welcome home". His vocabulary expands as the series progresses, often due to him mimicking other characters. Commander Wilbur Zero (voiced by John Bluthal): the operational commander-in-chief of the World Space Patrol and chief controller of Space City. Despite his gruff exterior, he shows great respect and care for his subordinates, especially Zodiac. Zero's rank appears to be above that of Colonel but below that of Space General. Lieutenant Ninety (voiced by David Graham): Space City's assistant controller. He is young, inexperienced and the one most often on the receiving end of Commander Zero's scathing attitude (although Zero also refers to him as "the best lieutenant Space City has"). In one episode he is shown training to be an XL pilot. Recurring Jock Campbell (voiced by John Bluthal): Space City's chief engineer, of Scottish origin. Eleanor and Jonathan Zero (both voiced by Sylvia Anderson): Commander Zero's wife and young son. Captain Ken Ross (voiced by John Bluthal): pilot of Fireball XL7. He often needs rescuing by the XL5 crew. Mr and Mrs Boris and Griselda Space Spy (voiced by David Graham and Sylvia Anderson): a villainous husband-and-wife pair of Russian origin who first appear in the episode "Spy in Space". The Subterrains (voiced by John Bluthal and David Graham): a race of hostile aliens from Planet 46. Production After making Supercar, production company AP Films (APF) presented its investor – Lew Grade of Associated Television – with two ideas for a follow-up series. One of these, titled Century 21 (the original name of the spaceship), was commissioned and produced as Fireball XL5. The rejected proposal, Joe 90, was about a boy called Joe who dreams of carrying out daring space missions as an astronaut codenamed "Joe 90". Unlike Century 21, this concept had a hybrid format – the fantasy sequences being filmed with puppets while the framing stories used live actors. The only creative element shared by the two ideas was the character of Professor Matic. APF would not revisit Joe 90 until 1967, when it developed a series of that title that bore little resemblance to the original idea. Century 21 drew inspiration from the Space Race of the early 1960s. Despite