Yukon Jack

Further reading Yandroth at the Comic Book DB Yandroth at the Grand Comics Database

Further reading Y'Garon at the Comic Book DB

Further reading Kagenobu Yoshioka at the Comic Book DB Kagenobu Yoshioka at the Grand Comics Database

Further reading Yukon Jack at the Comic Book DB Yukon Jack at the Grand Comics Database

Yandroth is an other dimensional technomancer in the Marvel Universe.

The character, created by Jim Lawrence and Dan Adkins, first appeared in Strange Tales #164 (January 1968). He has appeared sporadically as an opponent to Doctor Strange.

Within the context of the stories, Yandroth is the "Scientist Supreme" of the other dimensional planet Yann, and a would-be-conqueror who encounters and challenges Doctor Strange, as a counterpart to the latter's title of Sorcerer Supreme. Doctor Strange defeats Yandroth, sending him to fall forever through the Dimension of Dreams.

During his fall, Yandroth gains a degree of magical knowledge including how to gain more power by destroying a world. Returning to Earth, he constructs the "Omegatron". When his physical body is killed in a traffic accident, his spirit inhabits and activates the Omegatron. In this state he battles Doctor Strange, Namor, and the Hulk, the Defenders, intending to use their conflict to provide the Omegatron with the power to activate all nuclear stockpiles in a single explosion. Strange places Yandroth under a time displacement spell to defeat him, preventing him from triggering the explosion as time is now frozen for him.

When the Omegatron is released from the spell it is physically destroyed by the Defenders and Namorita, but Yandroth's spirit possesses a young female chemist. Later he uses this form to telepathically attack the heroes only to be defeated again. He is able to possess another host and sets in motion a plan to destroy the world. The original Defenders reform and stand against him. Learning that he is utilizing the captured form of Gaea to summon the monsters, they take the fight to him, disabling the spell needed to destroy the world, freeing Gaea, and destroying Yandroth. With his dying breath he curses the four who can barely stand one another so that they must come and work together in times of a severe crisis. This curse later revives Yandroth and gives him control over the four Defenders. He uses this in an attempt to destroy Yann.

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Wikipedia