Gay man, 64.
George Harrison
Tony Perkins
Frank Zappa
Dick van Dyke
Leonard Nimoy
Damn, most of them are dead already.
I believe that’s the first and last time I’ll ever see Frank Zappa on the same list as Dick Van Dyke.
Straight female, 37
Harrison Ford
Johnny Depp
Ewan McGregor (more towards 25 with the release of Trainspotting, for me.)
Mel Gibson, before the crazy set in.
Ciaran Hinds (also discovered Jane Austen flicks at that age)
Olivia Newton John
Any of the three original Charlie’s Angels
Cheryl Tiegs
lets revisit that memory. <bathing suit> Yup, still hawt. 
http://i.cdn.turner.com/sivault/multimedia/photo_gallery/0806/best.swimsuits.1970/images/Tiegsthefamousone.jpg
SM/43. Timeframe: the 80s.
Kathleen Turner
Sean Young
Sigourney Weaver
Ally Sheedy
Markie Post
Straight male. My 16-25 period occurred between 1983 and 1992. There was no way I could keep this to five and there are a number of titanium pins holding my right wrist together to prove it. So the list is not complete and is in no particular order.
Nastassja Kinski
Kathleen Turner
Beatrice Dalle
Wendy James
Rebecca De Mornay
Susan Sarandon
Michelle Pfeiffer
Sherilyn Fenn
Mary Elizabeth Mastrantonio
Carrie Fisher
Marisa Tomei
Susanna Hoffs
Jody Wately
Sheree J Wilson
Kate Bush
Straight male, 40, here. This would be 1986-1995. These are the celebs that I gratified myself to the most back when I was in my late teens/early twenties:
Lynda Carter
Shannon Doherty
Sigourney Weaver
Joan Lunden
Sherilyn Fenn
Straight men, age 48, putting my range here at 1977-1986.
Raquel Welch
Raquel Welch
Raquel Welch
Raquel Welch
Cheryl Ladd of Charlie’s Angels
Going on 35 this year…
Cameron Diaz
Jennie Garth
Jennifer Love Hewitt
Lisa Dean Ryan
Nikki Cox
Had a hard time actually getting it down to 5, and ended up picking all candidates who came on my radar in the earlier end of that range, specifically well before ‘Buffy’ hit the scene. 
Sophia Loren
Bridgette Bardot
Jane Fonda
Ursula Andress
Inger Stevens
Straight male, with those years falling late 1957-1966.
Kim Novak
Elizabeth Taylor
Sophia Loren
Jean Simmons
Shirley Jones
Born in '57, too, huh?
Male, 33.
Christina Ricci
Winona Ryder
Alyson Hannigan
Johnny Depp
Struggling to think of a fifth actually, but probably someone else from Buffy.
Jimi Hendrix
Paul Newman
Jim Morrison
James Garner
George Harrison
Damn, if I were straight, I’d be . . . you.
I don’t even remember anymore, except that Kurt Larson/Harland of Information Society was at the top. (He’s the middle one.)
Straight male, 39 (86-95)
Winona Ryder
Jennifer Connelly
Elisabeth Shue
Kristy Swanson
Rose McGowan
Female, 43
Steve Perry
Bruce Springsteen
Princess Diana
Prince
Michael Jackson
(I was more into music than t.v. And women apparently did not exist in my youth.)
Damn! Forgot about Jennifer Connelly. She should be in my list.