Diane was a California native who studied Drama at Santa Ana College before dropping out to study at the Neighborhood Playhouse in New York. After appearing in summer stock for several months, she got her first major stage role in the Broadway rock musical "Hair". As understudy to the lead, she gained attention by not removing any of her clothing. In 1970, Woody Allen cast her in his Broadway play "Play It Again, Sam", which had a successful run. It was during this time that she became involved with Woody and thereafter she appeared in a number of his films. The first one was the comedy Play It Again, Sam (1972) which was the screen adaption of the stage play. That same year Coppola cast her as Kay in the Oscar winning movie The Godfather (1972) and she was on her way to stardom. She reprised her role as Kay in the sequel The Godfather: Part II (1974) otherwise she appeared with Woody in Sleeper (1973), Love and Death (1975) and so on. In 1977, she broke away from her comedy image to appear in the chilling Looking for Mr. Goodbar (1977), which won her a Golden Globe nomination. It was the same year that she appeared in the Woody Allen movie Annie Hall (1977) and what an impact she made. She won the Oscar and the British Award for Best Actress and Woody won the Directors Award from the DGA. 

Diane started a fashion trend with her unisex clothes and was the poster girl for a lot of young males. Her mannerisms and awkward speech became well known. But the question being asked was -is she just a lightweight playing herself, or is there more depth to her personality. For whatever reason, she appeared in but one film a year for the next two years and those films were by Woody Allen. When they broke up, she was next involved with Warren Beatty and appeared in his film Reds (1981), as the bohemian female journalist, Louise Bryant. For her performance, she received nominations for the Academy Award and the Golden Globe. For the rest of the 80s she appeared infrequently in films, but she continued winning nominations in three of them. Trying to break her typecasting, she became the tool of the terrorist in the film The Little Drummer Girl (1984). To offset her lack of movie work, Diane began directing. She directed the documentary Heaven (1987), as well as some music videos. For television she directed an episode of the popular, but strange, "Twin Peaks" (1990). 

For the 90s, she has matured as an mainstream actress who reprised her role as Kay for the third Godfather film and Nina in Father of the Bride (1991) and Father of the Bride Part II (1995). In 1993, she once again teamed with Woody Allen in his film Manhattan Murder Mystery (1993) which was well received. In 1995, Diane received high marks for Unstrung Heroes (1995), her first major feature as a director.

Credit: imdb.com