Julian Grenier (died 1275) was the count of Sidon from 1239 to 1260, then becoming merely titular.
In 1260, he attacked adjacent areas of Damascus, killing a Mongol officer in the process.
The officer was the nephew of Kitbuqa, Mongol general of Hulagu Khan.
The Mongols avenged themselves by ravaging the territory of Sidon and sacked the castle.
He had an affair with Isabella of Ibelin, Queen of Cyprus, possibly prompting a papal letter, De sinu patris, condemning the relationship.