Patient Zero is the Earth-TRN028 version of Spider-Man and one of the main antagonists of the series starting with Season 20. Patient Zero is recruited by Yami Zelda in order to help her other half, Yami Bakura, ressurect Zorc Necrophades. Despite being killed by the heroes, Patient Zero returns after being revived by Yami Bakura. When Yami Bakura apparently kills Sephiroth, Patient Zero laughs sadistically at his death. Patient Zero then proceeds to battle Zombie Spider-Man on Icicle Mountain. However, he is defeated when Shadow the Hedgehog joins the fight. Patient Zero later teams up with Fabia Sheen after Yami Bakura states he is nothing more than a servant. Patient Zero ambushes Seto Kaiba later on, but decides not to duel him when he senses Yami Bakura's power increase. During Fabia's battle with the Heroes of Legend, Patient Zero intervenes to prevent Fabia from being cured. During The Keys of Smash Arc, Patient Zero battles alongside Yami Bakura against Zombie Spider-Man and Ren Krawler, but the fight is interrupted by Samus Aran, who betrays Yami Bakura and knocks Patient Zero away. During Season 21, Patient Zero fights alongside Yami Bakura and Ganondorf against Team Shadow. In Season 22, Patient Zero fights against the Heroes of Legend, but is killed by Goku's Spirit Bomb. Patient Zero is later revived by Sellon, but is sent back to the Home For Infinite Losers when she has a change of heart. Patient Zero is later revived due to The Offspring of Zorc's improper ressurection. Patient Zero reappears after a long absence in Season 32, where he is seen fighting The Punisher (Earth-TRN028) on their homeworld before Sonic the Hedgehog intervenes.
Patient Zero wears the same costume as Spider-Man, as he is an alternate reality version of the Wall-Crawler. However, Patient Zero has several holes in his costume, and lacks shoes. Patient Zero is also bulkier than Spider-Man and Zombie Spider-Man. Patient Zero also has extremely long fingernails and toenails.
Unlike Zombie Spider-Man, (who is also afflicted with a virus that was created by Yami Bakura) who is pure of heart, Patient Zero is very sadistic. He takes joy at seeing people suffer, and enjoys it even more when he commits massacre himself.
Patient Zero is quite powerful, as he was able to keep up with his zombie counterpart, who attained a great amount of power. However, his first proper battle ended in defeat, due to Shadow the Hedgehog joining the fight after it began.
|Zombie Spider-Man and Shadow the Hedgehog||Lose (due to Shadow joining the fight later)|
|Seto Kaiba||No Outcome|
|Zombie Spider-Man and Ren Krawler||Lose (Tag with Yami Bakura)|
|Heroes of Legend||Lose (Tag with Samus Aran, Ganondorf, Zombie Reed, Tobi, and Wiseman)|
|The Punisher (Earth-TRN028)||No outcome (due to Sonic's intervention)|