Andy Kaufman is dead as a doornail and he's NOT coming back, so says his last girlfriend -- who tells TMZ, she watched him die ... and the self-proclaimed "daughter" who revealed herself this week is a big fat phony. 56-year-old Lynne Margulies tells us, she was present inside the West Hollywood hospital room when Kaufman passed away in 1984 from a rare form of lung cancer. She was there, and she insists she saw him die with her own eyes.