Javal'tivon was the name of a Jem'Hadar First that Kitana'klan, who was claiming to be an envoy sent by Odo, claimed to have led a rogue Jem'Hadar attack against Deep Space 9 in April of 2376.
Kitana'klan, who was the actual leader of the attack, stated this to be the case when he was explaining his presence on Deep Space 9 shortly after the attack. He claimed Javal'tivon first attacked his ship on the Gamma Quadrant side of the Bajoran wormhole before preceding to attack the station. In fact it was Kitana'klan who had led the attack on the true envoy, Taran'atar, before preceding himself to attack DS9. (DS9 - Avatar novel: Book One)