Paltrow starred with Downey Jr. in the “Iron Man” franchise, while Aniston and fiancé Justin Theroux are personal friends of Robert and his wife Susan Downey. Theroux also wrote the screenplay for “Iron Man 2.”
Other stars who attended Jen's big holiday bash included Courteney Cox, Chelsea Handler, Paltrow's hubby Chris Martin, Jason Bateman, Tobey Maguire, Isla Fisher and Will Arnett.
"It's definitely Jennifer's favorite party of the year and something she looks forward to," a source told E! News. "The house was decorated beautifully and all of the white lights were stunning. Jennifer made sure every detail was perfect."