The designer of Doctor Who’s iconic villains, The Daleks, has passed away. Former BBC designer Ray Cusick died of heart failure in his sleep on Thursday, February 28, 2013, his daughter, Claire Heawood, told the BBC. He was 84.

“In the show, the race of Daleks was said to have been developed by a scientist to survive a war on their home planet of Skaro. However, the scientist was later killed by his own creation,” the BBC said. “The Daleks, mutants encased in studded, tank-like machinery that appear to glide over the ground, became a cultural sensation, with generations growing to love their famous electronic command of ‘Exterminate.’”