Hjalmar Poelzig is the primary villain of the 1934 film The Black Cat.
He was portrayed by the late Boris Karloff, who was also well-known for portraying Frankenstein's Monster in Universal Studios' Frankenstein films, Imhotep in The Mummy and Fu Manchu in The Mask of Fu Manchu, and for voicing The Grinch in How the Grinch Stole Christmas.
During the last years of World War I, Poelzig commanded Ft. Marmarous in Hungary, where his one-time friend and colleague Vitus Werdegast was also stationed. Poelzig sold out the fort to the Russians, and sneaked away, leaving Werdegast and the others to die.
Poelzig would later build his own house on the ruins of the fort he had betrayed. He would seduce and marry Werdegast's wife Karen, whom the doctor knew Hjalmar had always wanted "from the first time he saw her." He told her Werdegast had been killed.
When Karen died, the necrophiliac Poelzig preserved her in a glass case in the basement of his home, along with many other women. Poelzig then married her and Werdegast's daughter, also named Karen.
But Werdegast had not been killed. He was taken prisoner and spent fifteen years in a horrible prison camp, waiting to take his revenge on Poelzig. Once he was free, he traveled to Hungary, intent on killing Poelzig. He is accompanied by Peter and Joan Allison, a young couple on their honeymoon who are transported to Poelzig's house after getting into a car accident.
Poelzig shows Werdegast his wife's body, saying "Is she not beautiful?" Although Poelzig says she died of pneumonia, Werdegast suspects him of killing her. Poelzig lies to Werdegast about his daughter, claiming that she is dead, too. Later, Karen disobeys Poelzig and leaves their room and runs into Joan, who tells her her father is alive and that he has come for her. Poelzig leads her away and rapes and kills her.
Werdegast, unaware of what happened bides his time to take his revenge and save his daughter at the right moment, even playing a game of chess (both a real one and a metaphoric one) with Poelzig, to lull him into inaction.
After learning his daughter is dead, a heartbroken and enraged Werdegast fights a fierce duel with Poelzig, eventually overpowering him and skinning him alive. He then ignites a cache of dynamite hidden under the house, killing Poelzig and himself.
- Poelzig's name was borrowed from architect Hans Poelzig. His character is said to have been inspired by occultist Aleister Crowley.
- The Black Cat was the first movie that paired Karloff and Lugosi; it is widely considered their best film together.