From her Wikipedia page:
Yoko Kanno (菅野 よう子 Kanno Yōko, born March 19, 1964 in Miyagi Prefecture, Japan) is a composer, arranger and musician best known for her work on the soundtracks for many games, seminal anime films, TV series, live-action movies, and advertisements. She has written scores for famous animated works, including Macross Plus, Turn A Gundam, Cowboy Bebop, Vision of Escaflowne, Ghost in the Shell: Stand Alone Complex, Wolf’s Rain, and is the most trusted composer by veteran and new-wave directors such as Yoshiyuki Tomino, Shinichiro Watanabe and Shoji Kawamori. Kanno has also composed music for J-pop artists, the most notable being Maaya Sakamoto and Kyōko Koizumi. She is also a skilled keyboardist, and is the frontwoman for The Seatbelts, who perform many of Kanno’s compositions on the various original soundtracks for which she is responsible.