Lætitia Sadier (born 6 May 1968, sometimes known as Seaya Sadier, or “The Shah”) is a French musician best-known as the singer of the post-rock band Stereolab.

Sadier was working as a nanny when she met McCarthyleader Tim Gane at a gig in Paris during the late 1980s. Sadier was disillusioned with the rock scene in France, and soon moved to London to be with Gane and to pursue her career. She had contributed vocals to McCarthy’s third and final album. The band broke up in 1990 and she and Gane immediately formed Stereolab. For the first incarnation of the band, they enlisted ex-Chills bassist Martin Kean, drummer Joe Dilworth and Gina Morris on backing vocals.

While Tim Gane has written the bulk of the music in Stereolab, it is Sadier’s singsong, alto vocals and often revolutionary lyrics (both in English and French) that have become trademarks of the band’s sound. Sadier also plays keyboards, percussion, guitar (she’s left-handed) and trombone.

In 1996, Sadier formed the spin-off band Monade with Pram’s Rosie Cuckston.

Sadier has contributed vocals to various other groups and projects, at times along with the late Stereolab member Mary Hansen. Among her contributions were, adding French backing vocals on To the End, a top 20 hit for Blur in 1994. In 1995, Sadier had recorded the Serge Gainsbourg/Brigitte Bardot song “Bonnie and Clyde” with Luna.