Well..I obviously would have to say Monk.....that is a given...
I don't watch much tv anymore other than old movies on TCM so I am a little out of touch.........but maybe...he could appear on CSI...that would be cool. Or maybe in an episode of Lost...........Columbo on Gilligan's Island!!
You mean Columbo would find a way for the castaways to get off that ****ed island? Or maybe discover that one of the castaways a diabolic plot to wreck the ship and profit by it---he/she had insurance policies on all the parties and would collect millions if all were declared legally dead?