Seamus Patrick Dever (born July 27, 1976) is an American actor known for his role as Detective Kevin Ryan in the ABC series Castle.
A lifetime member of the Actors Studio, Dever married the future Juliana Dever on May 27, 2006. Juliana played Jenny Ryan, Ryan's wife, on Castle. He is a cousin of Broadway actress Jeanne Arnold and Canadian singer-songwriter Feist.Dever and his wife are vegetarians. Both are also supporters of Best Friends Animal Society.Dever also starred in a celebrity episode of The Chase (American game show), Season 3 (2014), where he scored 11 questions in the preliminaries, and led a team with Dean Cain to defeat the Chaser, Mark Labbett.
Dever was born in Flint, Michigan, and moved at the age of 6 to Bullhead City, Arizona, where he grew up. He graduated as valedictorian of Mohave High School, completed his undergraduate studies at Northern Arizona University, and holds MFAs in Acting from the Moscow Art Theatre and Carnegie-Mellon University.