Alfred Redl was an Austro-Hungarian officer, who rose to head the counter-intelligence efforts of Austria-Hungary. His term in office was marked by innovation, and he used very high technology for the time to ensnare foreign intelligence agents.

Redl was also a spy for the Russians---his motives for espionage are unclear, since he committed suicide not long after his exposure in 1912. He may have been caught in a compromising position by Russian agents, since he was homosexual and being exposed as such would have been fatal to his career prospects. At the same time, he was paid well for his services, and had a lifestyle far above what his official salary could cover.

Redl is thought to have passed a great deal of information to the Russian Okhrana, including plans for a future Austro-Hungarian offensive against Serbia. He also is believed to have betrayed various Russian officers who contacted Austro-Hungarian intelligence, allowing the Russians to capture them.

Redl's downfall came by accident, when he lost a pen-knife sheath in Prague, the third city of the Austro-Hungarian Empire. As it happened, the man who found it was a counter-intelligence man trained by Redl himself, and he noticed more and more anomalies, such as Redl receiving notes from Eydtkuhnen, East Prussia, a known border-crossing used by spies. When informed of his exposure, Redl committed suicide, which was regretted both by Emperor Franz Josef, who would have preferred that Redl avoid dying in mortal sin, and by Austrian Intelligence, which would have preferred to interrogate him on the exact extent of his betrayal.

Redl's treason is thought to have contributed to the defeats Austria-Hungary suffered in the early months of World War I, since the plans for the attack on Serbia were quite complete and could not easily be changed around in the time between Redl's suicide and the onset of the war.

He was played by Armin Mueller-Stahl in the 1985 film Colonel Redl .