Frank Buffay Jr. was a fictional recurring character in the popular television sitcom Friends which ran from 1994 to 2004. Frank Buffay Jr. was played by Giovanni Ribisi.

Frank is the half brother of Phoebe Buffay, named for their father. Phoebe discovered Frank on one of her attempts to find her father, who walked out on her when she was a child. It turns out that her father had left more than one family. Frank is perhaps even stranger than his older sister - he has a punctured lung, was arrested for stealing birds eggs, owned a dog called Tumour and believed that 'massage parlour' was a euphemism for a brothel, thereby wrongly assuming his sister was a prostitute.

In the third series (season) Frank announced to Phoebe that he was dating his home economics teacher, Alice (whom he accidentally continues to call 'Miss Knight'), played by Debra Jo Rupp . Although at first apprehensive, Phoebe realises that the two are genuinely in love.

In the episode 'The One With Phoebe's Uterus', Frank returned, now married to Alice, and asked Phoebe if she would act as a surrogate mother to them as they are desperate to have children, but they are not able to do so. Phoebe agrees and in 'The One Hundredth' gave birth to triplets - Frank Jr. Jr., Leslie and Chandler (named after Phoebe's friend Chandler).