A Rider introduced in the movie [i]"Kamen Rider W Forever: A to Z/The Gaia Memory of Fate":http://en.wikipedia.org/wiki/Kamen_Rider_W_Forever:_A_to_Z/The_Gaia_Memories_of_Fate [/i].

Joker is a form assumed by [[Hidari Shoutarou|Hidari Shotaro]] using his Joker [[Gaia Memory|Memory]] and a Lost Driver belt.
kamen rider joker