The Mad Thinker is a recurring antagonist in comics published by Marvel. He is mainly an opponent of the Fantastic Four, although he has fought other heroes such as the Avengers and the New Warriors. He was created by the late Stan Lee and the late Jack Kirby and debuted in Fantastic Four #15.
The Mad Thinker had been planning crimes for years, remaining unknown to the police. His calculations and computer power had allowed him to take advantage of apparently random events, such as knowing a hot dog stand would block the police after an armed robbery. He dreamed of establishing New York as an independent state with himself as its ruler but knew he would have to get rid of the Fantastic Four first. After arranging for them all to be away from the city for various reasons, he took advantage of a power failure caused by a meteorite strike to occupy the Baxter Building. He quickly came to understand Reed Richards' inventions and also built an Awesome Android to battle the FF when they returned. He nearly triumphed but the equipment deactivated at a crucial moment: Reed had arranged for Willie Lumpkin to press a button at a pre-arranged time that cut off the power.
Although he had named himself the Thinker, the press dubbed him the Mad Thinker and the name stuck. He allied himself with the Puppet Master, first using the X-Men to attack the Fantastic Four and then having the Thing and the Human Torch fight each other. He also took on the Avengers, assembling a team of supervillains to invade Avengers Mansion. His followers successfully subdued the known Avengers but he failed thanks to the presence of Hercules, who he had been unaware of. Mad Thinker also fought Iron Man during a supervillain contest but was defeated.
Despite his evil nature and hatred of the Fantastic Four, the Mad Thinker had scruples. He allied himself with the Wizard to abduct Franklin Storm, but on learning Wizard planned to carry out experiments that would almost certainly kill the child, he ended their alliance and helped the Thing capture him.
The Thinker contacted the New Warriors to leave a riddle for them, since he wanted them to help his nephew, who had developed super powers he was unable to control. During the Superhero Civil War, the Mad Thinker manipulated both sides with help from Puppet Master but was impressed by Reed Richards' predictive calculations.
More recently, with Reed Richards lost in another dimension, the Mad Thinker decided it was up to him to take on the role of Mister Fantastic. He used technology to give himself and his associates powers similar to the Fantastic Four and tried to kill Ben Grimm and Johnny Storm, the only members of the old FF he could find, but failed.
In addition to his comic appearances, the Mad Thinker has appeared in two animated series. He appeared in the Iron Man segment of Marvel Super Heroes voiced by the late Len Carlson, and in The Avengers: Earth's Mightiest Heroes voiced by Danny Mann.