After paying the bills in the mid-1960s, as her mother did, working as a dance teacher and secretary (per The LA Times), Marshall caught the acting bug and made a go of it in Hollywood in the late ’60s and early ’70s. Whoever booked talent for Head & Shoulders shampoo commercials during this period really had an eye for talent, casting Farrah Fawcett and Penny Marshall as roommates in one ad. Marshall then paid her dues on TV, winning small roles on shows like That Girl, The Bob Newhart Show, Love, American Style, and a made-for-TV movie called The Feminist and the Fuzz (Marshall portrayed “Liberation Lady”).
Marshall landed her breakout gig in 1972: the recurring role of Myrna, secretary to Oscar Madison (Jack Klugman) on The Odd Couple. A few years later, Marshall easily got the part of Laverne on Laverne & Shirley, not only because she previously played the character on Happy Days, but because the spinoff show was created obviously with her in mind — by her brother, TV writer and mega-producer Garry Marshall.