Complex sentence: Mulligan starred with Mariette Hartley in the 1966-67 comedy series "The Hero", in which he played TV star Sam Garret, who in turn starred on a fictional series as Jed Clayton, U.S. Marshal.
Split into simpler sentences: Mulligan starred with Mariette Hartley in the 1966-67 comedy series "The Hero". In the series he played TV star Sam Garret who in turn starred on a fictional series as Jed Clayton, U.S. Marshal.