Pitt, Cooper, Streep - wait, who's that guy?

Ellen's selfie at the Oscars has become a viral hit. Photo/Twitter

If Lupita Nyong'o had a night to remember at the Oscars then the same can surely be said of her brother Peter.

Not only did he accompany his older sister to the ceremony and get name checked during her emotional acceptance speech, but he also audaciously photobombed the star-studded selfie that has become the most retweeted ever.

The epic photo that broke Twitter features the crème de la crème of Hollywood royalty including Brad Pitt, Jennifer Lawrence, Julia Roberts, Meryl Streep and Bradley Cooper - and there rubbing shoulders with them all is Peter Feliz Anyang' Nyong'o, a first year student at Stetson University in DeLand, Florida.

Peter, one of the Oscar-winning actress' five siblings, has without a doubt just had a weekend he will never forget after accompanying his sister on Sunday night's red carpet.

When Lupita rose to give one of the evening's most emotional acceptance speeches for best supporting actress for 12 Years A Slave, he got an emotional name check.

Close to tears, she called him "Junior" and described him as her "best friend".

Afterwards when quizzed about his appearance in the star-studded snapshot, she laughed and said, "I think that's his win for sure".

"He got into the most famous selfie in the world. I'm glad I could have facilitated that."

In the famous Oscar night selfie, Nyong'o is positioned prominently on the right, cheekily blocking Angelina Jolie and his sister.

Peter has wasted no time in posting the iconic selfie of him hanging with the Hollywood elite on his Facebook page, while his profile picture is a touching photo of him posing with his famous sister.

His profile reveals that has spent time working at Hebron, a Chrisitian school in Tamil Nadu, India and his interests include a love of the British soccer team Arsenal and a rap group, The Flat 4 -1, that he launched with some friends while at school.

Peter is a freshman in the College of Arts and Sciences at Stetson, where he enrolled last year.

While older sister Lupita was born in Mexico City while their parents were in political exile in 1983, the family had long since moved back to Nairobi, Kenya, when Peter was born in the early 1990s.

By then, their father Peter Snr had become part of the country's senate, while their mother Dorothy had taken a leadership position with the Africa Cancer Foundation.

The six Nyong'o children's upbringing has been described as "middle class, suburban".

Until last year Peter was a student at St Andrews, one of East Africa's elite boarding schools and described as an international, multicultural, Christian Boarding School offering a British Curriculum education of the highest standard.

- Daily Mail