|Will Robert Pattinson play Christian Grey?|
The 'Twilight Saga' star asked the erotic fiction writer to come to his home in Los Feliz, Los Angeles, for the bash which he hosted for his friend, director-and-producer Nicholas Jarecki.
A friend of Rob's, singer Todd Michael Schultz, said: "It was a really good party. It was in Rob's backyard, he had catered tacos.
"E. L. James was there, she was really cool. Songwriter Diane Warren was a guest, Warren Beatty was there chilling."
Whilst it is yet to be confirmed who is in the running for the part of Christian Grey in the forthcoming adaptation of James' racy novel her attendance has sparked rumors that Robert may be cast as the male lead - an incredibly successful and wealthy young entrepreneur who enjoys a BDSM relationship with naive female lead Ana Steele.
However, one noticeable absentee from the party was Kristen Stewart - who Rob recently dumped after four years with her after he discovered she was back in contact with director Rupert Sanders, who she confessed to having an affair with last year.
Todd added: "Kristen Stewart was not at the party as far as I know."
The 'On The Road' actress returned to LA on Friday after enjoying a road trip with her friends through Texas, Louisiana and Tennessee.