Seamus Dever or Seamus Patrick Dever (born July 27, 1976) is an American actor. Dever is best known for his portrayal of Detective Kevin Ryan in the ABC series Castle.
Seamus Dever was born in Flint, Michigan, and grew up in Bullhead City, Arizona. He graduated as valedictorian of his high school class, completed his undergraduate studies at Northern Arizona University, and holds MFAs in Acting from the Moscow Art Theatre and Carnegie-Mellon University.
In addition to "Castle," Seamus Dever has played authoritative figures on the likes of "Army Wives" and "General Hospital" both of which had him starring as a doctor. Other forays into television include "Mad Men," "Drop Dead Diva," "NCIS," and all three "CSI" franchises. He's also appeared in such films as "Hollywoodland" with Adrien Brody and Ben Affleck, as well as the independent comedy "Ready or Not."