Markus Flanagan was born in Bucks Country, Pennsylvania. His television appearances include Judging Amy, CSI: Miami, Melrose Place, and Northern Exposure. He also starred alongside Christopher Walken and Matthew Broderick in the film Biloxi Blues, which is based on a play written by Neil Simon. His hobbies include biking, writing and playing baseball.

Jeff Singer is played by Markus Flanagan on Nickelodeon’s television series Unfabulous. He is the loving dad of Addie Singer, and he is having a puzzling time trying to figure out the activities of his teenaged daughter. He is one of those fathers who would love to keep their daughters young forever, instead of them growing up too fast.