Image: The Everett Collection

Every once in a while, the perfect actress comes along for the right part, and TV history is made. That's how we always think of Valerie Harper, who was cast as Rhoda Morgenstern on The Mary Tyler Moore Show when she was relatively unknown as an actress. She made the part her own, changing what was originally written to be an adversary into Mary Richards' closest confidante. She was rewarded by lines Moore tossed her way that helped immortalize the snarky humor — and led to the much-loved spin-off Rhoda.

Before Harper became Rhoda, she was a studied dancer, and her storied path to stardom starts in Radio City Music Hall, where she landed her first paying job as a replacement dancer in the Corps de Ballet. She was just 16 years old. From there, her career shifted a few blocks west to Broadway, where she performed as a chorus girl, turning up in productions like Wildcat, starring Lucille Ball. Oh, to see those two legends together on the same stage!

Harper landed a bit role in the film Li'l Abner, a 1959 adaptation of the popular comic strip. But did not move to Hollywood until 1968. One of her earliest gigs out there was co-writing an episode of Love, America Style. It involved a gorilla.

A talent scout for The Mary Tyler Moore Show spotted Harper performing theater in 1970. It was a quick rise to television stardom from there. The wedding episode of Rhoda became the most-watched television episode of the 1970s until Roots surpassed it. A whopping 52 million Americans tuned in to see Rhoda wed Joe. Only Lucy Ricardo's pregnancy had pulled those kinds of numbers in the past.

The Everett CollectionHarper was on of the earliest guest on 'The Muppet Show'

In 1987, Harper returned to the sitcom world as the titular star of Valerie, a family series that cast Jason Bateman as her son. After two seasons, Lorimar Productions and NBC fired Harper from the series and replaced her with Sandy Duncan, eventually changing the show to The Hogan Family. Harper successfully sued Lorimar and NBC and was awarded $1.4 million, plus 12.5% of the show's profits.

Over the past three decades, Harper has steadily worked on screen and stage. The 2000 made-for-TV movie Mary and Rhoda reunited the old friends. She turned up on everything from That '70s Show to 2 Broke Girls, from Sex and the City to Hot in Cleveland. In the last couple of years, she voiced characters on The Simpsons and Family Guy.

Throughout it all, Harper engaged in activism and charity. She fought for equal pay and fed thousands in Los Angeles.

In 2009, Harper was diagnosed with cancer. She passed away on Friday, August 30, according to her family and KABC. She was 80.

Tune in to Decades all week beginning Monday, September 9, as we present a special tribute to Harper featuring 'The Mary Tyler More Show' followed by 'Rhoda' 2p ET | 11a PT.

Watch The Mary Tyler Moore Show on Decades

Weekdays at 2p ET | 11a PT