- This article is about Phoebe Buffay's father. For her half brother see Frank Buffay Jr., for one of triplets she gave birth to see Frank Buffay Jr. Jr.
Frank Buffay Sr. is Phoebe and Ursula's father. He, Lily and Phoebe Abbott were involved in a sexual relationship together, which resulted in Phoebe falling pregnant with Phoebe and Ursula. Frank and Lily married and planned on raising the twins together. However, he walked out on his family and divorced Lily when the twins were just babies. He later remarried and had a son, Frank Buffay Jr., whom and his second wife he eventually abandoned as well.
Frank appears only once, when Phoebe's grandmother (Lily's mother), Frances, dies in "The One With Joey's Bag". He introduces himself at the funeral for the grandmother, which makes Phoebe gasp. He quickly says his name is Joe and rushes out. She catches up to him and claims she is the executor of Frances' estate, so he agrees to meet her at Central Perk after the funeral. Frank also did not know that Lily was dead, so he wanted to see her asking Phoebe to give her a letter he wrote to her. Phoebe then reveals to him that Lily is dead and also that she is actually Phoebe. He apologizes to her for abandoning her and it turns out that he sang her a lullaby as a baby to the same melody as "Smelly Cat". Phoebe smiles as he recites it ("Sleepy girl, sleepy girl, why won't you go to sleep; sleepy girl, sleepy girl, you're keeping me up.") At the end of the episode, Phoebe is not ready to forgive her birth father yet, but slowly warms up to him. They sit on the couch and talk for a while.
- The One With Joey's Bag (First appearance)