Dr. Hans Zarkov is the scientific genius of the Flash Gordon mythos and is the companion of Flash Gordon and Dale Arden.
Dr. Zarkov is introduced in the first Flash Gordon comic strip. Zarkov works in his "great observatory", building a rocket ship so that he can save Earth from colliding with Mongo. But the pressure proves to be too much for him -- "His great brain is weakening under the strain!", as the narrator puts it—and by the time he meets Flash Gordon and Dale Arden, Zarkov is "a madman" and "a disheveled, wild-eyed figure." Still, his invention works—the rocket takes off, and travels to Mongo.
The rocket crashes on the surface, and Zarkov is presumed dead. Flash rescues Dale from the crash and doesn't give another thought to Zarkov, until he shows up three months later, on April 24.
When the Sky City of the Hawk Men is about to topple from the sky, Zarkov invents an atomic Light solidifier, which stabilizes the city. A grateful King Vultan gives Zarkov a royal title: "Prince Zarkov of the Hawkmen, and Supreme Lord of All Scientists." 
Being that Zarkov worked with Lawrence Gordon and is supposed to be a mentor figure to Flash, he may have been in part the inspiration for Star Wars' Obi-wan Kenobi, as George Lucas said that the idea for Star Wars came from watching the Flash Gordon (serial)s as a child.
1980 Flash Gordon Movie
In the 1980 Flash Gordon movie, Dr. Hans Zarkov is an Earth scientist, formerly employed with NASA, who suspects that the environmental problems associated with the planet are a direct attack from outer space.
He is first seen sleeping across from his lab assistant, Munson, who is awakened by his burning blanket caused by 'hot hail.' Munson checks his watch and moves to wake Zarkov. Upon learning that it is 8:24 in the morning and there is no sunlight, Zarkov awakens immediately and orders Munson to check the angular vector of the moon. As he and Munson work on their instruments, a news report plays in the back ground explaining that Zarkov is the only one with an explanation for the problems, but that he has been dismissed as irrational. He asks Munson what his findings are and when the moon is out of orbit by more than 12 degrees, Zarkov confirms that he is correct and that they are under attack. Hot hail breaks through the glass roof and falls near him. He examines it and says that it is fragments of moon rock. The Moon is being subjected to an energy beam. He then tells Munson it is time to go and moves toward his rocket ship, planning to counter-attack. Munson says Zarkov is crazy and that he is not joining him into space. Zarkov pulls a gun on him and tells him to get his toothbrush and whatever else he needs, because he cannot handle the rocket controls alone. Munson turns and flees, but rather than shoot, Zarkov asks him why he is running away. Munson refuses to be a hero and Zarkov lets him go. Moments later, Munson returns, to a gleeful Zarkov, as the plane bearing Flash Gordon and Dale Arden comes crashing into the laboratory. Zarkov takes cover while the plane crushes Munson and comes to a stop.
Zarkov hides the gun behind his back and greets Flash and Dale, offering help and the use of his telephone. He tricks them into getting into the rocket capsule and brandishes the gun on them once he is recognized by Dale. A fight begins between him and Flash and his head hits the start button. The three of them strap themselves in as the rocket begins to take off. He tells Flash to step on the ‘red pedal’ and that friendship built the rocket to send in friendship. The g-forces cause them to pass out and the rocket heads for the Imperial Vortex. After crash landing on Mongo, the three of them are taken by strange guards into the Imperial Palace. Zarkov comments to Flash that whoever they are, the guards seem highly developed and that it might be possible to reason with them. Dale is not so convinced. They arrive at the palace and Zarkov believes that if they are in a police state, they could find allies of rebellion and thinks Flash should lead them. They are met by a wicked hovering robot who orders them to follow it. En route, it destroys a fleeing lizard man and after hearing Zarkov and Flash’s discussion about self-sacrifice, the robot destroys the gun in Zarkov’s pocket.
The trio make their way to the Grand Audience Chamber and witness the exchanges between the people of Mongo. They are brought before Ming when Flash makes an insulting comment about Ming, which the hovering robot overhears and broadcasts loudly. Ming wants to know who the trio are and Zarkov, during his turn, introduces himself as a scientist who kidnapped Flash and Dale in an attempt to save the planet Earth. Ming takes a liking to Dale and wants to see her more closely, but Flash tries to stop her. Zarkov halts him. Later, when Flash begins a rebellious fight to save Dale from being taken by Ming, Zarkov pulls free an egg-shaped item from a citizen of Mongo and throws it to Flash, who, as a football player, regains his senses after being stunned and proceeds to battle the guards, with Zarkov supplying him with 'footballs.' Unfortunately, Zarkov hits him in the head with one and knocks him out. Ming states that Flash will be executed, Dale will be taken for Ming's pleasure, and that Zarkov will be delivered to Klytus for conditioning by the Imperial Secret Police.
Later, at the execution of Flash, Zarkov is present in an upper viewing area with Dale and helps her when she panics. Zarkov is next seen strapped to the Mind Wipe device, where Ming tells Zarkov he is the reason Earth is being destroyed and that Zarkov recognized the hand of Ming as being responsible. His mind is then wiped of memories by the Mind Wipe machine while Klytus and Kala watch. He is supposed to be reprogrammed with Level 3 conditioning, but the evil Kala orders the technician to program it at Level 6, which is clearly a horrible process.
Zarkov is then seen standing at attention before Klytus and Kala. Klytus asks him his name and he says “Hans Zarkov” but quickly covers and says “Agent Zarkov, number 2133 of the Imperial Anti-insurgent Espionage Group. Hail Ming!” Which appears to satisfy Klytus. Zarkov is later ‘activated’ by Kala when Dale attempts to escape the palace. Zarkov intercepts her, where Dale tells him that Flash is alive and that he is in Arboria. Suspicious, Klytus and Kala allow them to leave the city to track them, but while fleeing on a rocket cycle, Zarkov tells Dale he retained most of his memory by thinking of Shakespear, the Talmud, the formulas of Einstein, and even a song from the Beatles to keep his memories intact. They are intercepted by Hawkmen and taken to Sky City, where Zarkov confronts Vultan, telling him he knows that Vultan is only waiting to attack Ming. He attempts to convince Vultan to attack, but Vultan is reluctant because his weapons are not ready.
Later, before they see Flash again, Zarkov calculates the Moon will crash on the Earth in roughly 14 hours, 9 minutes, and 20 seconds. He then watches the battle between Flash and Barin, commenting on Flash’s humanity when Flash saves Barin. When Klytus arrives in Sky City, Zarkov learns he will be liquidated for treachery, but Klytus is killed by Flash. Flash, Dale, Barin, and Zarkov are left in Sky City when the Hawk Men flee. Flash wants to parachute to Arboria, Dale says it is deadly, but Zarkov assures them the body reaches maximum velocity within a few hundred fleet. Ming’s ship arrives and Zarkov attempts to signal their surrender. He, Dale, and Barin are taken aboard and Flash is left to confront Ming.
Zarkov is chained in the dungeons with Barin awaiting execution, and is apparently telling Barin stories about Houdini. Aura arrives and saves them, but when she attempts to access the elevator with her power ring, she finds the code has been changed. While Aura and Barin talk about how they have changed their ways, Zarkov accesses it by guessing that it was one of the prime numbers of the Zeeman series, stating ‘he hasn’t changed.’ He and Barin then storm the headquarters of the Secret Police cyborg agents and he tells Barin to grab an imager off of one of the agents, which destroys the entire array of cyborgs. Kala shoots her flamethrower ring at Zarkov, but Barin kills her. Thanking Barin, Zarkov then says they have to deactivate the lightning field and asks Barin where the atomic generators are, but they are 6 miles underground. Barin leaves Zarkov to ‘hold the fort’ while he flees and Zarkov walks by the decomposing body of General Kala, watching as it dissolves into a murky black liquid. He tries unsuccessfully to deactivate the lightning field.
At the finale, Dale asks Zarkov if they will ever be able to leave Mongo. Zarkov responds that he does not know, but that they will try.
Sci Fi Channel
As a graduate student, Zarkov worked with Flash's father, Lawrence Gordon on the Portage Initiative, developing technology to explore Rifts between Earth and other planets. He now works in a laboratory located in a warehouse, monitoring rifts. He's very aware of the American government's cover-ups, and has become somewhat paranoid.
Dr. Zarkov through the years
- Maurice Franklin: The Amazing Interplanetary Adventures of Flash Gordon (1935)
- Frank Shannon: Flash Gordon (1936), Flash Gordon's Trip to Mars (1938), Flash Gordon Conquers the Universe (1940)
- Joseph Nash: Flash Gordon (1954)
- Alan Oppenheimer: Flash Gordon (1979)
- Topol: Flash Gordon (1980)
- Bob Holt: Flash Gordon: The Greatest Adventure of All (1982)
- Paul Shaffer: Flash Gordon (1996)
- Jody Racicot: Flash Gordon (Sci Fi Channel) (2007)
- Flash Gordon (comic strip): "Friends, bah! You're spies!"
- The Amazing Interplanetary Adventures of Flash Gordon: "I know you for what you are -- spies!"
- Flash Gordon (serial): "Stop! Stay where you are."
- Flash Gordon (1979 cartoon): "They seem to be mutants, bred to live in the sea."
- Flash Gordon (movie): "No sun? Check the angular vector of the moon."
- Flash Gordon (Sci Fi Channel): "Please don't touch me. I don't like being touched."
- ↑ Flash Gordon (comic strip) comic strip. January 7, 1934.
- ↑ Tournaments of Mongo. November 25, 1934.
- ↑ Flash Gordon (serial) serial, "Chapter 101: The Planet of Peril".
- ↑ Flash Gordon (serial) serial, "Chapter 111: In the Claws of the Tigron".
- ↑ Flash Gordon's Trip to Mars, Chapter 201: New Worlds to Conquer, 1938.