Sean Penn Sued -- Photog Claims Death Threat

Sean Penn threatened to kill a paparazzo if he ever ran into him again ... this according to a new lawsuit filed by the photog.

Jordan Dawes alleges he was filming a documentary about paparazzi last October in Brentwood, CA when Penn suddenly began "kicking and punching" him.

In the suit, filed in L.A. County Superior Court, Dawes says Penn broke his camera and then said "the next time I see you, you will be in a box."

As we first reported, Dawes said he had to have knee surgery ... the result of the alleged attack.

Penn was charged with criminal battery and vandalism over the incident back in February. That case is pending.