Amanda Buffamonteezi (Jennifer Coolidge) - Introduced in "The One with Ross' Tan" (Season 10, 2004) as an annoying lady who used to live in the building before moving to England. She picks up a fake British accent and claims to have slept with Evil Knievel.
She calls Monica's apartment, and after Chandler answers and bemuses her by informing her that he has pedicures before handing the phone to Monica, she asks if Monica and Phoebe could meet up with her in the coffee shop. There she inadvertently reveals that Phoebe had wanted to cut Monica out of her life in 1992, as Monica was at the time driving Phoebe mad by being, in Phoebe's words "controlling and compulsive and shrill." Although Monica is upset by this information, Phoebe later reassures her that she is glad now that she changed her mind after realizing what a nice person Monica was despite all of this. The two make up.
It is never revealed exactly why Amanda moved away from Monica and Phoebe, but given her inflated ego and self-absorbed attitude, it is likely that she, like Phoebe at first, couldn't stand Monica's controlling, compulsive and shrill nature. She seems to really like both Monica and Phoebe however, most likely because she knows they're nice people really, seeming genuinely pleased to see them both again, and looking genuinely upset when she realized she'd upset Monica, when it became clear that Monica was hearing that Phoebe had wanted to cut her out of her life in 1992 for the first time.