38 days until Hellboy Day - Leopold Kurtz
Leopold Kurtz was one of the trio of Nazi scientists, along with Ilsa Haupstein and Professor Doctor Karl Ruprecht Kroenen, that dedicated their lives and intellects to their master, Rasputin.
From an early age, Kurtz showed an enormous talent for science. In 1935, at age of 20, he was invited by Heinrich Himmler to join the German Occult Bureau. He joined the group alongside Dr. Herman Von Klempt and Dr. Kroenen. It was Kurtz that saved the life of the former during an experiment gone awry. The form we most recognize von Klempt in, a floating, living, head in a jar, is due to Kurtz’s ingenuity; a choice that he would come to regret.
After Project Ragna Rok summoned Hellboy to Earth, he and his two colleagues entered cryogenic sleep in a secret base in Norway. Awoken after the events of Seed of Destruction, Kurtz was the first to greet Roderick Zinco, attacking the CEO with a Nazi Robot exo-suit. When Zinco brought the preserved head of Herman von Klempt to Kroenen, Kurtz protested. When he overheard von Klempt’s treasonous plans against Rasputin’s, the short tempered Kurtz became violent. Kroenen regretfully stabbed him in order to protect the mad scientist.
We saw him laid out on the table, dead by all appearances, while Kroenen lamented, and endured von Klempt's taunts. Rasputin appeared and caused Zinco to go blind, then activate the self-destruct mechanism of the castle. It appeared to all that Zinco, Kroenen, von Klempt and Kurtz were incinerated in the blast. Over a decade later, though, Kurtz was still somehow alive and unharmed, with Kroenen at the Zinco headquarters. They appeared to have allied themselves with the new CEO Marsten in order to continue to utilize the Zinco resources in order to summon Rasputin’s spirit back to Earth.
Once again, Kurtz had misplaced his trust in Zinco. This led to another failure in assisting his Master, Rasputin. Marsten tricked Kurtz and Kroenen into summoning what the CEO thought to be Pope, but was instead the Black Flame. During an assault on New York in an attempt to liberate it from the Black Flame, Leopold Kurtz was captured by the B.P.R.D. He was being held in B.P.R.D. headquarters in Colorado, which was evacuated while under attack by Ogdru Hem. It is not clear if he made it out, or died in the onslaught, and as the end is nigh, we may never know.
Edit: apparently still alive.
Places to see Kurtz in the Mignolaverse:
Wake the Devil
Russia (Hell on Earth)
The Devil’s Engine (Hell on Earth)
The Return of the Master (Hell on Earth)
Reign of the Black Flame (Hell on Earth)
End of Days (Hell on Earth)
Rasputin: Voice of the Dragon