Spencer suggested it in the anime thread, so we're gonna do it.
The Big OThe story takes place forty years after a mysterious occurrence causes the residents of Paradigm City to lose their memories. The series follows Roger Smith, Paradigm City's top Negotiator. He provides this much needed service with the help of a Gynoid named R. Dorothy Wayneright and his butler Norman Burg. When the need arises, Roger calls upon Big O, a giant relic from the city's past
Director: Kazuyoshi Katayama [Appleseed OVA, Argento Soma, Those Who Hunt Elves]
Writer: Chiaki J. Konaka [Armitage III, Hellsing, Serial Experiments Lain, Ghost Hound, Shadow Star Narutaro]
Music: Toshihiko Sahashi [Gundam SEED, Full Metal Panic, Hunter x Hunter]
Aired: 1999-10-13 to 2000-01-19 and 2003-01-02 to 2003-03-27
Episodes: 26
Random fact: The second season was released 4 years after the first because of the series' success on Cartoon Network [who co-produced the second season]