Madoc is well known to fans of Doctor Who for multiple appearances relating to the series, almost always playing villains. He acted a small role in the second Peter Cushing film, Daleks' Invasion Earth 2150 A.D. (1966), and was later cast in the television series itself four times. He appeared in two Second Doctor serials, The Krotons (1968) as Eelek and The War Games (1969) as the War Lord. He appeared in two Fourth Doctor serials, The Brain of Morbius (1976) and The Power of Kroll (1978-79). He recorded DVD commentaries for The Krotons, The War Games and The Brain of Morbius and was interviewed about his roles in Doctor Who in the short film "Philip Madoc - a Villain for All Seasons", which appeared as an extra on the DVD for The Power of Kroll. He revealed in the interview that he regretted taking the final role (The Power of Kroll) because it was a less interesting character. In 2003, he guest-starred in the Big Finish Doctor Who audio adventure Master, and returned to Big Finish in the 2008 Sixth Doctor story Return of the Krotons. He voiced the War King in the Faction Paradox audio series.