Letterle is from Northfield, Ohio, but moved to New York in 1997. After stints as a chorus member and dancer in many musicals and dinner theaters he went to the La Scala in Italy where he was a featured dancer in West Side Story. He later played "Doody" in a production of Grease in Berlin before returning to NYC. Daniel ventured into film as an extra in various movies before being cast in a lead role for Camp (2003). Letterle lived in Los Angeles for about a year pursuing various projects culminating in a starring role in the film adaptation of a comic strip, The Mostly Unfabulous Social Life of Ethan Green (2005). He returned to Ohio the following year where he continues to live a relatively normal life.