Lætitia Sadier, also 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.