We know who the biter is in the Beyonce mystery ... we're told it's none other than Sanaa Lathan.
Multiple sources tell TMZ, Tiffany Haddish has told multiple people the culprit is Sanaa.
One source said it was not an aggressive bite ... it was playful and noninvasive, but still caught Beyonce off guard.
Sanaa tweeted a faint denial, saying "Y'all are funny. Under no circumstances did I bite Beyonce and if I did it would've have been a love bite."
The incident in question went down in December, at an after-party for Jay-Z's 4:44 concert at The Forum.
The story goes ... Sanaa was talking to Jay in a way that made Bey uncomfortable. Beyonce went over to Sanaa who brushed off any insinuation of inappropriate conduct and then gave her a jokey bite.
Tiffany told Beyonce she was going to kick Sanaa's ass, but Bey told her to let it go.