Kenichi Matsuyama (松山 ケンイチ, Matsuyama Ken'ichi, born March 5, 1985) is a Japanese actor. He is known for his affinity for strange character roles, and he is best known internationally for playing L in the 2006 films Death Note, Death Note 2: The Last Name and L: Change the World in 2008. He was cast to play lead character Toru Watanabe in the film adaptation of Haruki Murakami's novel Norwegian Wood, which was released in December 2010.

His stage name uses the katakana spelling of his first name (ケンイチ) instead of the usual kanji (研一).

He graduated from Tokyo Metropolitan Toyama High School.

He debuted as a model in 2001 for PARCO. He made his acting debut in the television series Gokusen in 2002 and made his first film appearance in Bright Future in 2003. He starred in the film Winning Pass a year later.

Matsuyama starred in Ultra Miracle Love Story in 2009, using the Tsugaru dialect of Japanese in the film.

He voiced the role of Balthazar Bratt in the Japanese dub of Despicable Me 3 in 2017. He was in the stage play Seven Souls in the Skull Castle the same year.

He played a police detective in the 2023 drama Why Didn't I Tell You a Million Times?^[1]

On April 1, 2011, he married Koyuki Katō, who co-starred with him in Kamui Gaiden.^[2] The couple's first child was born in January 2012,^[3] and their second child was born in January 2013 in South Korea.^[4] In July 2015, the couple had their third child.^[5]

He speaks in the Shimokita dialect.