ATHENS, Greece - U.S. equestrian Robert Dover is among the rarest of all 10,500 athletes in Athens, not only for his six Olympic appearances but because he is one of a tiny handful of competitors who publicly identifies himself as gay.

Dover — along with some prominent ex-Olympians who came out after retiring — believe there are scores of other gay and lesbian athletes in an array of sports at these Summer Games, either fully in the closet or confiding only to a small circle of people.

Gays and lesbians may be able to marry in a few European countries, and now Massachusetts, but it’s another era on the Olympic field of play.

Dover, a three-time bronze medalist who is captain of the dressage team, said many gay athletes simply want to stay focused on their performance and worry that publicizing their sexual orientation could lead to distractions.

“But there also are many athletes afraid to come out because of their peers, or their coaches or their loved ones having negative feelings,” Dover said. “We have to keep on showing the world that — just like straight people — we’re going about our lives, doing the very best we can to make our country and our families proud.”

GAY AND LESBIAN OLYMPIANS OF THE PAST Some athletes of past Olympics who made it known, either during or after their careers, that they were gay or lesbian: —Tom Waddell, a U.S. decathlete who competed in the 1968 Olympics. He founded the Gay Games in 1981 and died of AIDS in 1987. —John Curry, British figure skater who won the gold medal in 1976. He died from an AIDS-related illness in 1994. —Bruce Hayes, who won gold in the 200-meter freestyle relay at the 1984 Olympics, later set world masters records at the Gay Games. —Holly Metcalf, gold-medal-winning U.S. rower in 1984. —Greg Louganis, widely considered the greatest diver of all time. Won four golds in diving at the 1984 and '88 Olympics. Came out in 1994. —Mark Tewksbury, Olympic backstroke gold medalist for Canada in 1992. —Mia Hundvin of Norway and Camilla Andersen of Denmark, who not only played against each other in team handball at Sydney in 2000, but also were legally married in Denmark. —Brian Orser, a two-time Olympic silver medalist in figure skating for Canada, who in 1998 lost a legal battle to prevent the public disclosure of a palimony suit filed by a former boyfriend.

Mark Tewksbury, who came out as gay six years after winning a gold medal for Canada in the backstroke in 1992, says Dover is lucky to compete in a sport considered unusually accepting of gays and lesbians.

Swimming — like most other Olympic sports — is different, Tewksbury said. He recalled his anguish at lacking the nerve to object, and reveal his sexual orientation, when teammates used “fag” as their insult of choice.

“I got so tired of lying, of living a double life, I felt like I was going to die,” said Tewksbury, 36, who is in Athens covering the Olympics for the Canadian Broadcasting Corp. “I was afraid of being beaten up, afraid my coach would stop coaching me, afraid my teammates would reject me.”

Tewksbury has become an activist, campaigning for athletes’ rights in general and specifically promoting programs — such as a planned OutGames 2006 in Chicago— to encourage gay athletes.

Among his occasional colleagues is Holly Metcalf, a gold-medalist U.S. rower in 1984. Metcalf, 46, lives near Boston with her 4-year-old daughter and her partner of nine years, whom she plans to wed now that Massachusetts recognizes same-sex marriages.

Metcalf said it is unfortunate, though understandable, that so many gay Olympians are reluctant to come out.

“It often comes down to financial considerations,” she said in a telephone interview. “You’ve got so many women moving into collegiate sports, with a lot more money there now, and you have lesbian coaches who think, ’Oh, my God, if anybody finds out, I’ll get fired.’ Colleges don’t want to deal with this.”

Gay rights has been a high-profile issue in recent years, with landmark court rulings, a nationwide debate over gay marriage and — on the eve of the Olympics — New Jersey Gov. James McGreevey’s stunning announcement that he would resign because of complications arising from an extramarital affair with a man.

Through it all, many gay Olympians remain cautious — most won’t come out until there are gay gold medalists saying, “Hey, don’t be afraid,” Metcalf said.

A common pattern for gay Olympians is to come out after retirement — four-time diving gold medalist Greg Louganis is an example. He revealed in 1994 that he was gay and HIV positive, and later wrote a candid autobiography.

OutSports, a U.S.-based web site devoted to gay sports, tried to tally the number of openly gay and lesbian athletes competing in Athens and came up with only six — including Dover and tennis players Martina Navratilova and Amelie Mauresmo. Dover suggests there are scores more not ready to be open.

“You spend a day with these athletes, and it becomes obvious that gay people are everywhere,” Dover said. “The reason many of them aren’t out is because they’re focused on their job during this time when sports is the No. 1 thing in their lives.”

Dover, 48, kept mostly quiet about his sexual orientation until 1988, when he met fellow rider Robert Ross, his partner ever since. Dover manages a stable near his home in Lebanon, N.J., spends winters in Wellington, Fla., a riding mecca near Palm Beach, and oversees a foundation which assists people in the horse world who have HIV or AIDS.

While Tewksbury believes full acceptance of gay Olympians may take many years, Dover is heartened by ongoing changes. He cited an appearance by the five gay stars of the hit TV show “Queer Eye For The Straight Guy” in a film shown to American athletes by the U.S. Olympic Committee to help them prepare for Athens.

“It’s proof that things are moving along,” Dover said.