Green, glowing rocks. As well as red, gold, blue, white, jewel, silver, black, orange, pink, and periwinkle. All of the kryptonite variety.
Superman does not fear any noble gas. In the "Death of Superman" comic storyline, Superman is killed by Doomsday, not a noble gas.
Keychains with pictures of kittens on them.
Superman has stated that the only man he's afraid of is Batman, and with good reason.
Superman was brave because he was fearless. Superman doesn't take no for an answer, he just punches that no in the face. Ain't nobody mess with superman, not even batman. This fear of Superman by the general public fuels his bravery and enables him to rule metro city.
utimate superman (strongest) superman prime one million superman prime superboy prime sowrd of superman cosmic armor superman all star superman sun dipped superman aplopit cyborg superman evil cyborg superman cyborg superman steel superman modern age blue superman eradicator superman red/blue ultraman bizzoro ad superman ga superman sa superman green latern superman pre crisis superman (weakest)
ultimate superman (strongest) superman prime one million superman prime super man with sowrd of superman tough robot superman all star superman cosmic super man silver superman pre crisis superman normal superman (weakest)
Superman Superman Returns Superman II Superman III Superman IV: The Quest for Peace Waiting for Superman Superman/Doomsday The Batman Superman Movie: World's Finest Superman/Batman: Public Enemies Superman/Batman: Apocalypse All-Star Superman Leaving Metropolis (which was called 'Poor Superman' in Canada)
superman
"Superman" (1948) "Atom Man vs Superman" (1950) "Superman and the Molemen" (1951) "Superman: The Movie" (1978) "Superman II" (1980) "Superman III" (1983) "Superman IV: The Quest For Peace" (1987) "Superman Returns" (2006) "Man of Steel" (2013)
Superman: The Movie Superman 2 Superman 3 Superman 4: The Quest for Peace Superman Returns There's also Superman: Doomsday which isn't part of the live action series. It's a stand alone animated version.
ultimate superman (strongest) superman prime one million superman prime superboyprime sowrd of superman superman one million tough robot superman all star superman cosmic super man superman red/blue golden age superman silver age superman red son superman ultra man bizzor superman (weakest)
Superman, Batman doesn't have any powers