Marsha is Ross' colleague in the Museum of Prehistoric History in "The One With The Sonogram At The End". She is played by Merrill Markoe.
Marsha is first seen working with Ross in the caveman section of the museum. Carol shows up to announce to Ross about her pregnancy, Ross tries to ignore her but Marsha starts talking to her. Ross sends Marsha to the ice age section saying that he will catch up with her soon.