The answers (that we know of) are:
Robert Maschio
Tate Donovan
Matthew Perry (2003-2004)
Marc Blucas (2005)
Some more info on Lauren:
Name: Lauren Helen Graham
Eye Color: Blue
Hair Color: Dark brown
Birthplace: Honolulu, HI
Religion: Roman Catholic
High School: Langley High School, McLean, VA (1984)
University: New York University, New York, NY; Columbia's Barnard College, New York, NY (BA in English, 1988); Southern Methodist University, Dallas, TX (MFA in Theater, 1992)
Family: Her parents divorced when she was 5. She was raised by a single parent, her father.
Father: Lawrence Graham (former president, Chocolate Manufacturers Assn.)
Mother: Donna Graham (fashion executive, div. Lawrence Graham in 1971)
Step-mother: Karen Graham (stepmother, business consultant, m. Lawrence Graham in 1981)
Risk Factors: Smoking 
