He really is a very little man in a big world. No. Literally. Introduced in Fantastic Four Annual #5 by Stan Lee and Jack Kirby, this scientific minded ruler is from a planet in the Microverse. Overcrowding of his planet lead him to try and find a solution with the idea of moving his people to Earth being his idea. To make this possible he study human behaviour and created a device to manipulate their emotions. He also created a massive exoskeleton that he used in the Prime Universe. 

He began experiment on humans but was thwarted by the F4 a number of times. He would eventually try and obtain the Uni-Power, the energy force behind Captain Universe. He capture all that were chosen but was defeated by Spider-man with the help of the other former Captain Universe. He gave up on finding the Uni-Powers and instead created an android Hate Monger. He also used his powers to corrupt Sue Storm into Malice and had her attack and defeat the F4. After Reed helped her break free, they chased Psycho-Man into the Microverse, where Sue got her revenge by using the emotion controlling device on Psycho-man. He would return later but was defeated by Earth’s heroes.

Psycho Man is a little known but requested character. As such he has received a few figures over the years, with the first Marvel Legends version being an homage to the Toybiz 90’s Animated version as part of Hasbro’s Fantastic Four retro wave.