UFC 200 -- Former Fighter's Death Threat Against Dana White ... Plans To Show with Gun

Dana White's at the receiving end of some scary death threats from a former fighter who allegedly claims he's gonna show up up to UFC 200 with a crew and guns to kill the UFC honcho.

Sources close to White tell TMZ Dan Quinn -- who never fought in the UFC, but had a lengthy fighting career -- is angry over some unresolved bad blood. Back in 2012 Quinn allegedly threatened to shoot Dana in the head and has been in and out of prison since on an unrelated weapons charge.

We're told Quinn recently contacted Dana again and now says he's got tickets to Saturday's big fight and his target is Dana. Our source says Quinn has threatened to bring guns and a crew to attack.