No,not the TV show but none other than Marlo "Ann Marie" Thomas!
I guess it shouldn't be "that" suprising,given how long ago the series was. It's quitrte the coincidence because just the other night I got to re-watch her 1974 special,"Free To Be You and Me". (Love that title song by The New Seekers!)
I saw That Girl" in reruns as a kid & teen and thought she was a pretty cool girl.

I thought "Donald" was ...wel,a duck! (Looked like.)
I most recently saw her on one of the very few episodes of Friends I've ever watched as the mom of one of the characters.
Happy 70th Marlo!!
(and also a happy birthday to Goldie Hawn @ 62!)