|“||I challenge you to a duel! I shall defeat you to avenge the Koopa Klan and all the brave Koopasss that you have sssso callousssly ssssstomped upon. Including my besssst friend! [...] Don't feign ignoranccce with me, you missserable plumber. He wasss sssstationed at Bowssser'sss Cassstle in Dinosssaur land many yearssss back. Room #2, Koopa 3. Don't you remember? Not only did you crush hisss shell, but you kicked him into the lava, too. Now, for the ssssake of all the beingss that have sssuffered becaussse of your mindlesssss actionssss, I shall be victoriousssss. I could ssssimply turn you to ssstone and grind you to dusst, but I would rather take delight in liking the blood from your corpsssse after the battle. The Underwhere awaitssss you!||„|
|~ Basilisx explaining his hatred for Mario while preparing to fight him.|
Not much is known about the history of Basilisx, but, according to him, he was originally one of the many Koopa guards protecting Bowser's castle during the events of Super Mario World. When Mario stormed the castle in order to rescue Princess Peach, he killed one of the Koopa guards by kicking him into lava, but unknown to him, that particular guard was actually Basilisx' best friend. Because of that action and how he doesn't feel any emotions or regret towards ruthlessly killing Koopa soldiers, Basilisx developed a very deep personal hatred for Mario. It is assumed that his desire to kill Mario is what lead to Basilisx going from a normal Koopa to a (supposedly) cybernetically enhanced soldier, who he was presumably turned into by Dr. Eggman and Bowser, as he was not around before they started working together.
He is much faster, stronger, and an overall better fighter than any of Bowser's soldiers, even able to defeat and poise to kill Hammer Mario (though it should be noted that to do this, he used the stone encased Luigi as a way to halt Mario's attack, and use two poison mushrooms to remove his hammer form and severely weaken him).
Basilisx's raspy voicing and speech, the play on words "this demonic super-soldier" on Episode 8, his shadow like appearance, and his vicious fighting suggests a demonic personality. However, he claims to have deep sadness regarding the fatal lava-scalding of his "besssst friend", Koopa #3 of Room 2 in Bowser's Castle. However, this may have been an untrue excuse to kill Mario because there is no lava in Room 2. (Technically, there are no Koopas in Room 2, and there isn't a Bowser's Castle.)
- According to Alvin-Earthworm, Basilisx will be omitted from the remake. It was stated that while Basilisx was well-received by the fans, the creator had felt Basilisx served no purpose from the lack of background storyline and history in the franchise.
- The way Basilisx summons his claws is incredibly, most likely intentionally similar to the way Marvel Comics character Wolverine does.
- Basilisx claims that Mario killed his best friend in Room #2, Koopa 3. by kicking him in the lava, however, this is inaccurate to the games, as, not only is there no lava in said room, but no Koopas either.
- Given this fact and Mario's lack of memory on the event, it is possible that Basilisx was actually lying about his backstory to justify his desire to kill Mario, or that he was programmed into thinking this by either Eggman or Bowser.