5. Bob Gibson
Famed as one of the meanest players ever, Gibson had one of the most badass deliveries in baseball history, and was never afraid to send a message pitch. He hit his friends who got traded to other teams (Bill White), he threw brushback pitches at Old Timers' games. And he changed the game—literally. After his epic 1968 season in which he held batters to a .184 batting average and struck out 268, the pitching mound was lowered by 5 inches to help batters. No matter, in 1969, he struck out 269.