Ken'ichi Matsuyama (松山 研一/松山 ケンイチ, born March 5, 1985 in Mutsu, Aomori, Japan) is a well known Japanese actor.
He is known for his affinity for strange character roles. He is best known for playing L in the 2006 film Death Note, Death Note: The Last Name and L: Change the WorLd in 2008, as well as voicing Gelus in the Death Note anime adaptation. He has recently performed in the dual role of Soichi Negishi/Johannes Krauser II in the film adaptation of Detroit Metal City.