Before the show
Ross and Carol's Wedding
Barry & Rachel's Wedding
Carol & Susan's Wedding
Barry & Mindy's Wedding
The Season 2 finale took place at Barry's wedding to Mindy Hunter.
Frank Jr. & Alice's MarriageIn Season 3, Phoebe's brother Frank Buffay Jr. revealed that he was going to marry a woman, Alice Knight, 26 years his senior. While it bothered Phoebe at first, Frank and Alice showed that they were truly in love. Joey and Ross were so touched that they became the best man and ring bearer respectively. However, in the Season 4 episode, "The One With Phoebe's Uterus", Frank and Alice reveal that they had decided to simply get married at the Courthouse, while having lunch.
Ross & Emily's Wedding
In the middle of Season 4, Ross meets Emily Waltham, a woman from London. After knowing each other for only six weeks, they decide to get married. This ends disastrously, however, when Ross says Rachel's name at the altar. To make matters worse, Ross was going to take Rachel to the honeymoon until he saw Emily and chased after her. They finally got a divorce when Ross said he cannot live without seeing Rachel and that was Emily's only demand.
Ross & Rachel's Marriage
In the Season 5 finale, Ross and Rachel stumble drunkenly out of a wedding chapel in Las Vegas. In the morning, neither of them remember the event and agree to get it annulled. When Ross decides that he cannot have three failed marriages, he decides not to get the annulment and stay married to Rachel... without her knowledge. Eventually, Rachel finds out, and tries putting a disastrous end to their short-lived marriage. However they took the reason for the annulment overboard and were forced to get a divorce.
Cousin Franny's Wedding
In The One With All The Cheesecakes, Monica learns that her cousin Franny is getting married, but did not invite her to the wedding. To make matters worse, she learns that Ross ("and guest") did get invited. Monica forces him to bring her as his guest so she can confront Franny. At the wedding, Monica asks her "what [she] could have possibly done" to make her not invite her. At that moment, the groom approaches. It is Stuart, one of Monica's ex-boyfriends. Ross tells her "it's more of a question of who could you have done."
Chandler & Monica's Wedding
The season 7 finale revolves around the long-awaited marriage of Chandler and Monica. In this marriage, Chandler runs away because he is frightened by the thought of being the "Bings." Ross and Phoebe finds him in his office and helps him have the courage to get married. Also Phoebe starts telling people Monica is a pregnant bride because she saw a pregnancy test which was actually Rachel's. Also Joey is stuck doing his movie and almost misses being the minister but he makes it just in time and marries Chandler and Monica. Phoebe and Rachel are the bridesmaids. Ross is the best man.
Phoebe & Mike's Wedding
In Season 10, Phoebe married long-time boyfriend Mike Hannigan. When their wedding was almost cancelled due to a blizzard, they decided to have the ceremony outside of Central Perk in the snow. Because the minister could not make it, Joey married the two of them. Rachel and Monica were both bridesmaids, Chandler gave Phoebe away, and Ross held Mike's dog, Chappy.
Janice and Gary Litman
Janice and Gary marry early in the show off-screen, possibly in Season 1 or 2.
Janice and Sid Goralnik
At some point before "The One Where Rachel Has A Baby, Part 1," Janice and Sid marry.