Ice Cube's BIG3 league kicked off this weekend with its first games ... and with them came a gaggle of big-time A-listers to watch.

Cube held his first games Sunday in front of 15k fans at the Barclays Center in NYC, and besides the stars on the court, there were a ton of others in the stands. They included Whoopi Goldberg, LL Cool J, James Harden, Jalen Rose, Lou Williams, Paul Pierce, D'Angelo Russell, Naturi NaughtonFabolous, Michael Rapaport and others -- most of whom got some shots in with Cube ... photos, that is. 

The BIG3 league rolls on through the summer, and is scheduled to conclude with a championship game at the T-Mobile Arena in Vegas. Unless Floyd and Conor have something to say about it.

The games air tonight on FS1.