So, let's explore some of those instances where the threat was fulfilled and Superman went on a rampage, exposing his real (?) evil side.
Let's start with the Justice Lords, an alternate dimension version of the Justice League. There, the superpowered members of the Justice League, led by Superman, rule Earth with an iron fist. Just to be clear on the subject, that version of Superman fried Lex Luthor with his heat vision and then proceeded to take over the Earth, coincidently lobotomizing everyone who stood in his way, various supervillains included.
In the game Injustice Gods Among Us, Superman is tricked into killing Lois Lane and then really goes on a rampage, freely killing everyone who stands in his way to the new world order he creates.
Superboy Prime is another alternate version of Superman from another dimension. Although starting off as good, a combination of circumstances made him turn to evil and he became one of the evil and most powerful supervillans that ever plagued the DC multiverse.
In the animated Superman series, Darksied captured Superman and brainwashed him, putting him at the head of his armies and sending him to rampge across the Galaxy, conquering planets in a spree of wanton destruction that ended on Earth.
In The Call episodes of Batman Beyond, Superman is being mind controlled by the alien Starro. Under his control, Superman tried to murder his Justice League friends and attacks batman beyond himself.
In the animated movie Superman Doomsday, Lex Luthor clones Superman and tried to control the clone, using red sun radiation and kryptonite. But the close breaks out of Luthor's control and then immediately starts to rampage (sounds familiar?), killing everyone who stands in his way, including the villain Toy Man and directly confronts the army, shooting planes and helicopters out of the skies and burning tanks with impunity.
In conclusion, what do we have here? An alien being who turns to evil so many times on so many occasions, that we can only wonder at those times he didn't turn to evil. True, some of those times he was brainwashed or cloned or was from another dimension but still, you cannot but wonder at the depth of evil he could reach and did reach on so many occasions.
סדר בחדר - סידור ארונות, חדרים ובתים