When Diana Ross turns 75, Hollywood's A-list come out to celebrate! And that includes Beyonce -- from one diva to another, the Queen B serenaded Ms. Ross with the traditional "Happy Birthday" song at Ross' blowout bash in West Hollywood Tuesday night.

In attendance were P. Diddy, Ashlee Simpson and Evan Ross, Leonardo DiCaprio, Robin Thicke, Khloe and Kourtney Kardashian and mom Kris Jenner and many, many more. Khloe stunned in a floor-length gold lame dress with her hair curly and teased big in a tribute to Diana. Kourt wore a silver sequin suit with black bra and she posted a glittering video to her Instagram story to document the look.



Diana herself even performed her class "Stop, In the Name Of Love." Happy birthday, queen!