LONDON - Gerry Anderson, puppetry pioneer and British creator of the sci-fi hit "Thunderbirds" TV show, has died. He was 83. Anderson's son Jamie said his father died peacefully in his sleep on Wednesday at a nursing home near Oxfordshire, England, after being diagnosed with mixed dementia two years ago. His condition had worsened dramatically over the past six months, his son said. Anderson's television career launched in the 1950s. Once "Thunderbirds" aired in the 1960s, "Thunderbirds are go!" became a catchphrase for generations. It also introduced the use of "supermarionation" , a puppetry technique using thin wires to control marionettes , and made sci-fi mainstream, according to Jamie Anderson. "He forever changed the direction of sci-fi entertainment," Jamie told the Associated Press. "Lots of animation and films that have been made in the past 20 or 30 years have been inspired by the work that he did." He said the TV show was perhaps his father's proudest achievement , along with the cross-generational appeal of his body of work, which also included TV shows "Stingray" and "Space: 1999," among others.