Lætitia Sadier (born 6 May 1968, sometimes known as Seaya Sadier) is a French musician who was formerly a founding member of the London-based avant-pop band Stereolab. While a member, she formed her side project Monade in 1996 to play her own solo songs; and retired the project in 2009 to perform new solo work under her name. Sadier has also occasionally appeared in guest vocals and collaborations.