Allison Williams is an American actress, comedienne and musician best known for her starring role as Marnie Michaels in the dark comedy-drama television series Girls.
Williams was raised in New Canaan, Connecticut. She attended Yale University and graduated in 2010. While at Yale, Williams was a member of the improv comedy troupe Just Add Water for four years.
In 2010, she performed a mashup of Nature Boy set to RJD2's A Beautiful Mine, the theme song for the television series Mad Men. The YouTube video of the performance received widespread praise on the Internet and convinced family friend Judd Apatow that she should be given a part in the HBO TV series Girls.
She was cast shortly after and credited her experience at Just Add Water for passing the audition.
Williams also wrote a series of Funny or Die sketches in which she starred as newly wed Kate Middleton.
She is the daughter of NBC Nightly News anchor Brian Williams.