#1 Tony Stewart
While Tony Stewart is no doubt one of the best drivers ever to lace up a par of gloves in NASCAR or in Indycar, he is also a very controversial figure that has let his temper get the best of him several times. One of those times was during a Sprint Car race in 2014, where he struck and killed dirt track racer, Kevin Ward Jr after an on track accident.
Of course Kevin Ward Jr shares some of the blame in this incident for walking onto the racing surface and confronting The former Cup Series champion, but it was Stewart that aggressively accelerated his race car and killed Kevin Ward Jr. Believe it or not, Stewart was never suspended or banned Stewart for the incident, but he did take time off after the incident to cope with what happened.
In the end, Stewart gave NASCAR an extremely bad name with his unprofessional actions at the dirt track that night and he should have been reprimanded for it. Furthermore, he should have been at least suspended from the sport for a period of time in order to make sure that Stewart was mentally fit to compete or if his anger problems would cause trouble once again.