Mia Farrow has twin boys; Ron Howard twin girls;
Michael J. Fox twin boys (I think); and Richard
Thomas identical triplet girls. Anyone else?
George W. has twin daughters (18 years old, I believe).
Cybill Shepherd has twin daughters.
Jane Seymour has twin sons.
Time to do research.
Cybill Shepherd’s twins are boy/girl, not two girls.
That’s almost right, Cybil has a girl (Ariel)
and boy (Zachary).
Hubert Putlizer has twin sons with ex-wife
Roxanne. I read her book about their nasty
divorce.
Ingrid Bergman had twins, one of which is Isabella Rossellini.
These are probably going to come to me one by one.
They’er all having kids late, so they’re hooking down the fertility drugs. This often lead to multiple births.
Adrienne Barbeau gave birth to twin boys on March 1997.
Ok, did some searching at IMDb so this is only famous people in TV and Movies (my requirement here for famous was that I recognized their name when scanning a list).
[Interesting note: Andy Garcia was born with a conjoined twin the size of a tennis ball, non-viable]
Twins:
Ingrid Bergman: daughters
Robert DeNiro: sons
Milos Forman: sons
Steve Harvey: daughters
Lee Majors: sons
Henry Mancini: daughters
(damn, just got called into a spontaneous 90 minute meeting so all these names have probably been said)
Lou Diamond Phillips: daughters
Ray Romano: sons
Jimmy Stewart: daughters
Rip Torn: sons
Triplets:
Richard Thomas: daughters
No claims that this is complete and I notice that neither Cybill Shepherd and Ray Romano came up in my search.
Patricia Richardson (mom from Home Improvement) had just given birth to twins (don’t know if it was boys/girls/mix) when the show started.
Trivia. I live for it. 
Dr. Drew of Loveline fame has triplet 7-year-old boys.
Meanwhile…how about celebs that are a twin? Alanis Morissette comes to mind first; she has a fraternal twin brother.
Linda Hamilton (Terminator, etc.) has an identical twin sister. She was used in the apocalyptic scene of T2: Judgement Day; that was her on the playground, with Linda behind the chain link fence screaming helplessly for “herself” to leave.
Celebs that are twins: The Olson twins (ugh)
Jeremy and Jason London ::swoon::
Marlena from the soap Days of our Lives has a twin sister
Physicist/science-fiction novelist Gregory Benford has an identical twin, James Benford.
James is also a physicist/author, although he writes physics textbooks, not novels.
Jill Hennessy and Linda Hamilton both have twin sisters.