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The information in this article comes from Warlord of Mars: Dejah Thoris and is not written by Edgar Rice Burroughs.

Senneth Dor was the Jeddak of the kingdom of Yorn 437 years before John Carter arrived on Mars. Senneth Dor is also the father of Dor Valian.


When the war between Lesser and Greater Helium neared finish Senneth Dor announced the marriage of his son to Dejah Thoris, this created a temporary peace because both the cities owed their loyalty to Yorn. Once the leaders of both cities were gathered to witness this union he took them hostage to gain control of the cities.

After he gained control he searched the catacombs beneath Lesser Helium, there he found the colossus during all of this great green horde of the north led by its Jeddak Kreshid Var began to attack helium, challenging the Jeddak directly. More than ever Sanneth Dor desired the power of the Colossus, he was angered by the attack and began beating on the colossus demanding that it work. His demands where answered when the colossus absorbed him and he took direct control, he used the power of the colossus to turn the tide of battle against the Green Martian horde.

He commenced a campaign of genocide against the green race of Barsoom. In the first two weeks of this campaign he eradicated three tribes of the race. He spared no member of the race that he could find.

When a convocation of Jeddaks of various nations was held in secret in the Tharsis Mountains, Senneth Dor had a spy amongst them, the Jeddak of Zodanga, and was able to ambush them, thus inadvertently uniting his enemies when they escaped. After that he began to lay seige to Ptarth, while his fleets hunted down the navies of the red nations.

His son Dor Valian worked hard on a device to that would disrupt the colossus brainwaves. When the device was activated Senneth Dor was exposed, Dejah Thoris was able to fly close with an invention of Dor Valians and kill the Jeddak of Yorn and by extension the colossus.



Death was not the end for the Jeddak of Yorn, though his body was obliterated his head survived. The scientist Vas Argus found the head and re-animated him, turning him into a Machine Man. He assumed the name Mortus and became the leader of an assassin guild in the Barsoomian underworld, slowly destroying the other guilds and having many Helium noblemen assassinated.

Vas Argus and Senneth Dor intended to created an army of Machine Men in order to change the face of Barsoom. This mostly involved the abduction and murder of prostitutes from Zodanga's Avenue of Pleasure.


Senneth Dor is a demented madman, but at the very least he is able to act the part of a king worth the loyalty of his subjects, feigning kindness and respect. He is fairly intelligent, but not to any extreme level. When he acquired the Colossus he was able to calm the hostilities between Lesser & Greater Helium long enough to gain control of both cities by taking the cities leaders hostage. Senneth Dor greatly disliked his son Dor Valian, seemingly because his son did not live up to his expectations. When he stole his sons research to uncover the Colossus his son was greatly angered, but he disrespected him so much he couldn't even begin to grasp the idea of his son being a threat.

When he fused with the colossus his madness was amplified a thousand times, seemingly because of the great power he had. With the power of the colossus he intended to wipe out the Green Martians.

He has a burning hatred for the green men of Barsoom. The mother of his son was a concubine which he truly loved and intended to marry, but she died in his arms during a green ambush. This is probably the reason for his hatred of them.



Senneth Dor did not have any abilities worth noting, that is until he came into possession of the Colossus. He fused with the colossus, it effectively became an extension of himself, a giant towering monster capable of projecting blasts of energy from its mouth and hands.

Following his resurrection as a Machine Man he demonstrated capable leadership abilities in the running of an underworld Assasins Guild, as well it is presumed his new body gave him abilities different from a typical Red Martian.