February 18, 1895 - December 14, 1920: Age 25
"I've got to go, Rock. It's all right. I'm not afraid. Some time, Rock, when the team is up against it, when things are wrong and the breaks are beating the boys, ask them to go in there with all they've got and win just one for the Gipper. I don't know where I'll be then, Rock. But I'll know about it, and I'll be happy."
This is the famous speech that young George Gipp spoke to his coach, Knute Rockne, while on his deathbed. Gipp (better known as "The Gipper") was a brilliant player for Notre Dame when he died. Apparently he was out after curfew one night, and was forced to sleep outside. By morning he had contracted pneumonia and died of a related infection. Some say, however, that he contracted strip throat after his final game on November 20.
Whatever the cause, Gipp ended up on his deathbed giving the speech that would live famously on for decades. After his death, Rockne used the story and the line "Win one for the Gipper" to inspire the team to an underdog victory. Twenty years later, in 1940, Ronald Reagan played Gipp in the film Knute Rockne, All American and earned the nickname "The Gipper".
The story does not end there. Responding to an allegation that Gipp had fathered an illegitimate daughter, born five days after his death, the medical examiner ordered an exhumation and DNA testing using his femur. (The result: he had not.) Some members of Gipp's family objected to the proceedings (which were filmed for ESPN) and have filed a lawsuit alleging that the remains of Gipp's sister were disturbed by the exhumation.
Sources: Wikipedia, SLAM Sports