Merriman's other roles include the horror films "" (2002), "The Ring Two" (2005) and "Final Destination 3" (2006). He starred in "Home of the Giants", a high school drama. He appeared in the CBS miniseries "Comanche Moon" in January 2008. He played Henry Dunn in the original pilot presentation for "Harper's Island", but was replaced by Christopher Gorham when the series was picked up by CBS. From 2010 to 2014, Merriman portrayed Ian Thomas on ABC Family's "Pretty Little Liars". In 2012, he starred as Dennis Mack in the 16th episode of Season 2 in "Hawaii Five-0".