Did you watch American Horror Story Hotel? If you remember the character James March, I bet you didn't know that he was based on an actual person.

Herman Webster Mudgett was born in New Hampshire in 1861. He was born into privilege and was said to be very intelligent and had an interest in medicine. However, there were definitely some rumors about him from early on. Apparently, he would "practice surgery" on animals and he was questioned in the death of a friend. It was later found out that while in medical school, Holmes would steal the bodies of corpses and use them to make false insurance claims. There are speculations that he used these bodies in his experiments as well.

Herman Webster Mudgett changed his name to Holmes after abandoning his wife and child in 1885. He then moved to Chicago and was working at a pharmacy when it is believed he started swindling money from his employers. With this money, he purchased an empty lot in Chicago and build his 'Murder Castle.'

The building featured soundproof rooms, trapdoors and secret passages that lead guests through a maze of hallways and staircases. In the basement was a facility Holmes used to get rid of the bodies. It featured a crematorium and vats of acid. Some rooms had five doors while others had none. You could open a door that only had a brick wall behind it. Sometimes, it would be impossible to find your way out.
Holmes was able to trick so many people into staying at his hotel by promising them cheap lodging during the Worlds Fair.

Holmes also had a habit of getting engaged to women who would suddenly "disappear."

Holmes was arrested after attempting to fake his assistant's death for insurance. In prison, he told his cellmate about his plan and the cellmate later helped investigators to catch Holmes. He claimed to have killed more than 200 people at his Murder Castle, including his assistant and his two daughters. Some theorists even believe that Holmes was Jack the Ripper, a serial killer that to this day has gone unidentified.