Lætitia Sadier, sometimes known as Seaya Sadier, is a French musician best known as a founding member of the London-based avant-pop band Stereolab. She was born in the east of Paris and spent time in the US as a child. In 1996, while Stereolab was still active, she formed the side project Monade. In 2009 – the same year Stereolab became inactive – she ended the Monade project and began to perform solo work under her own name; her current band is known as the Lætitia Sadier Source Ensemble. She has frequently performed guest vocals and collaborations with other artists.

Stereolab are an Anglo-French avant-pop band formed in London in 1990. Led by the songwriting team of Tim Gane and Lætitia Sadier, the group's sound features influences from krautrock and 1960s French pop music, often incorporating a repetitive motorik beat with the use of vintage electronic keyboards and female vocals sung in English and French. Their lyrics have political and philosophical themes influenced by the Surrealist and Situationist art movements. While performing, they play in a more feedback-driven and guitar-oriented style. From the mid-1990s, the band began to draw from funk, jazz and Brazilian music.