Sylvia Anderson, co-creator of the hugely popular science-fiction puppet series Thunderbirds and the voice of the show’s Lady Penelope, has died at the age of 88 after a brief illness, her family and website confirmed Wednesday. Anderson’s career took her from iconic status in the childens’-television industry to a spin as head of programming for HBO in the UK.

Sylvia Anderson Who Was The Voice Of The Original Lady Penelope In The Thunderbirds Tv Series At The Film Premiere Of Film Thunderbirds At The Empire Leicester Square London Pictured With Lady Penelope's Pink Car From The FilmAnderson and her late husband Gerry Anderson created electronic marionette puppets and a process they called Supermarionation, in which the voices were recorded first. The puppets’ heads had sensors connecting to the tapped dialog so that their lips were synchronized with the soundtrack. In 1963, they developed Thunderbirds, a futuristic series about a family that runs a secret organization dedicated to saving human life. Lady Penelope, a glamorous agent, was modeled on Anderson herself, and she provided her instantly recognizable aristocratic voice to the role.

The Thunderbirds spun off two feature films and a toy and merchandise empire. Three new programs were filmed last year to mark the show’s 50th anniversary. In a career spanning five decades, she also worked on Stingray, Fireball XL5, Secret Service, Joe 90 and Captain Scarlet, as well as becoming a programming executive at HBO. In 1981 she divorced Gerry Anderson, who died in 2012 after suffering from Alzheimer’s disease.

Born in south London to a boxing promoter and a dressmaker, Sylvia Anderson graduated from the London School of Economics with a degree in sociology and political science. She worked in the U.S. as a journalist before joining a British TV production company, where she met her future husband. They founded AP Films and began producing puppet shows.

Anderson is survived by her daughter, Dee Anderson, a singer and songwriter; and a son, Gerry Anderson Jr., an anesthetist. She also leaves four grandchildren and one great-granddaughter.