Sylvia Beatrice Anderson was an English television and film producer, writer, voice actress and costume designer, best known for her collaborations with Gerry Anderson, her husband between 1960 and 1981. In addition to serving as co-creator and co-writer on their TV series during the 1960s and early 1970s, Anderson's primary contribution was character development and costume design. She regularly directed the fortnightly voice recording sessions, and provided the voices of many female and child characters. She also helped develop the shows and characters, in particular creating the iconic characters of Lady Penelope and Parker in Thunderbirds.

Thunderbirds is a British science fiction television series created by Gerry and Sylvia Anderson, filmed by their production company AP Films (APF) and distributed by ITC Entertainment. It was made between 1964 and 1966 using a form of electronic marionette puppetry combined with scale model special effects sequences. Two series, totalling thirty-two 50-minute episodes, were filmed; production ended with the completion of the sixth episode of the second series after Lew Grade, the Andersons' financial backer, failed in his bid to sell the programme to American network television.