Martin Luther King, Jr.

Many people only know Martin Luther King, Jr. from the surviving film clips. You might not know that he started college at age 15. He had skipped ninth grade, and then during World War II, Morehouse College battled a decline in enrollment by accepting high school juniors if they could pass the entrance exam. King passed, and enrolled in 1944. Considering that he was born in January, that's three years younger than normal, so he must have started elementary school early.

As a child, he tried to kill himself by jumping from his home's second story window -twice. The first time was when he thought he'd killed his grandmother. The second time was when she really died, of a heart attack, and he blamed himself.   

There are a ton of sources you can read about King, but you can get an overview by starting at Wikipedia. 

Martin Luther King, Jr. was only 39 when he was shot and killed in Memphis.