Several dozen high-profile celebrities expressed their remorse over social media following the death of former teen heartthrob David Cassidy, who passed away Tuesday at the age of 67 after suffering organ failure. Cassidy was best known for his role as Keith Partridge on the 1970s sitcom "The Partridge Family." "Star Wars" actor Mark Hamill tweeted, "Very hard to #GetHappy right now. My condolences to his family, loved ones & the millions who idolized him around the world.
