Petar Kružic (died 1537) was a Croatian knez, captain, soldier and defender of Klis, and the captain of Senj.
In the early 16th century Petar Kružic (knez of Klis) defended the Klis Fortress against Turk invasion.
He died in 1537 trying to break yet another siege of the Turks.
After his death, the Klis defenders agreed to give the fortress to the Ottomans in exchange for their women, children and their own lives.
In this way, the Ottomans finally conquered the Klis Fortress after almost two and a half decades of its successful defense.