Oskar Paul Dirlewanger (26 September 1895 – c. 7 June 1945) was an SS officer and a war criminal. He was the commander of the penal unit known as the Dirlewanger Brigade, considered to be the most notorious part of the Waffen-SS. His unit epitomized the expansion of the war of terror in its most brutal form, with Dirlewanger himself regarded as perhaps the Nazi regime's "most extreme executioner." He died after the war while in Allied custody.

Dirlewanger had an impressive career as a junior officer during World War I. He further fought in the post-World War I conflicts in Germany as a minor commander in the Freikorps militia movement, with the troops he led then also characterized by excessive violence, and participated in the Spanish Civil War. He was also a habitual offender, convicted in the interwar Germany for raping a child and other crimes. During World War II, Dirlewanger was appointed and headed a special SS unit that was officially named after him and was composed for the most part of conscripted convicts and other prisoners. Serving mostly in Poland and Belarus, he has been closely linked to many atrocities, being responsible for the deaths of at least tens of thousands. His methods included rape and torture, and he personally kept numerous women as his sex slaves. He is also noted to have committed the worst crimes of the bloody suppression of Warsaw Uprising. Dirlewanger's brutality was not limited to civilians and captured enemy combatants, as he was ruthless to his men, whom he would beat and kill if they displeased him. His unit is regarded as the war's most infamous in Belarus, as well as Poland, and arguably the worst military force in modern European history based in terms of criminality and cruelty.