Gabrielle Union is a baaad woman -- she just fired back at Stacey Dash and took down Ronda Rousey as collateral damage in her feud with Dash.
We got Gabby at LAX Tuesday ... on her way back from the Sundance Film Festival, where she dissed Stacy for suggesting the BET Awards should be canceled to make the Oscars more diverse. Gabby's reaction was the classic ... "Stacey Dash who?"
Watch the clip ... Ronda got dragged into this when photogs hinted Union and Dash's beef might get physical.