Tanner James Maguire is an American child actor. On House, M.D., he portrayed Jack Randall, the sick son of a billionaire in the Season 6 episode Instant Karma. Maguire has been acting professionally since the age of 7 with an appearance on Medium. Since then, he has appeared in Desperate Housewives, Days of Our Lives, How I Met Your Mother, Letters to God and The Hangover: Part II. He often plays the younger version of other characters on television series.