His origin story begins when a scientist by the name of Dr. Mark Erdel teleports him to Earth. The scientist has a heart attack and dies leaving the Martian to become stranded on Earth. He is forced to disguise himself, while using his powers, to look like a human and becomes a police officer. He starts to go by the name of John Jones, a police detective. He uses his powers to help the people of Earth in various ways. His origin story has become slightly changed over the years. Like how Mars was dead when John came to earth or how martians worshiped a large flaming skull figure known as "Dream". He is a very valuable member of the Justice League and one story even puts him in "The Justice Society of America" which was an earlier form of the Justice League.
Injustice: Gods Among Us
Martian Manhunter hid at Atlantis for 5 years. By using shapeshifting, he took the form of an Atlantean Royal Archivist.