Koopaphobia is a persistent fear of Koopas, mentioned only during The Super Mario Bros. Super Show! episode "Raiders of the Lost Mushroom". Indiana Joe is the only known character to have been afflicted with Koopaphobia, as the mere mention of Koopas caused him to shiver uncontrollably. How Indiana Joe developed his Koopaphobia is unknown, although it may be an allusion to Indiana Jones's own fear of snakes.
Indiana Joe is aware of the fact that the legendary Lost Mushroom is found within the Temple of Koopa, but due to his Koopaphobia, he never musters up the strength to venture inwards, as the entrance itself is shaped like a crowned Koopa's head. Instead, he eventually meets up with Mario, Luigi, Princess Toadstool and Toad, and leads them to the Temple of Koopa, telling them to enter, while he waits outside.
Indiana Joe is eventually scared off by Kolonel von Koop and the Koopa Pack, and returns to his home. Realizing that he can no longer be a treasure hunter due to his Koopaphobia, Indiana Joe starts his own babysitting service. Later, he discovers that the three Mushroom brats he is babysitting are even scarier than Kolonel von Koop himself, and he ultimately overcomes his Koopaphobia to help Mario's group recover the Lost Mushroom.