In no particular order:
#1 Georgetown 50, #16 Princeton 49. Until 2018 UMBC's epic blowout win over Virginia, this was the closest a #16 seed had beaten a #1 seed during March Madness. The Ivy Leaguers had 2 shots in the final 15 seconds to win the game but both were snuffed out by future NBA star Alonzo Mourning. The NCAA had been considering eliminating the automatic bid champions from smaller conferences received to the Big Dance, but this game effectively put an end to that line of stupidity.
Phi Slamma Jamma -- IMO, 1982-83 Houston was probably the best team never to win it all -- somehow losing to NC State in the 1983 NCAA Division 1 Men's Basketball Tournament Championship Game. Okay, the Cougars bricked too many FTs even with Olajuwon & Drexler.
Ohio State 75, Cal 55 in the 1960 NCAA Championship. Just a friendly reminder Illinois fans that the Buckeyes have won a NC in men's basketball. Probably should have won 1 of the next 2 championships, but lost both games to Cincinnati -- which didn't have Oscar Robertson.