Len Bias
One of the greatest, if not, the greatest college basketball players of all time. Len Bias wasn't a McDonald's All American coming out of high school, but got better and better every year until he became the best player in college basketball. Played at the University of Maryland from 1983-1986. Has been compared to Michael Jordan as far as skills on the court. Played against Jordan in college and always seemed to get the better of him when they played against each other. Bias was a back-to-back ACC player of the year in '85 & '86. Len Bias was drafted into the NBA on June 17, 1986, second overall in the first round by the Boston Celtics. Died tragically two days later, June 19, 1986 of cardiac arymethmia, resulting from a cocaine overdose.
There's a chance that had Len Bias lived, Michael Jordan would not have had six NBA Championships. Maybe 4 but not six.