Mr. Mxyzptlk was created to appear in Superman #30 (September / October 1944), in the story "The Mysterious Mr. Mxyztplk" (the original spelling), by writer Jerry Siegel and artist Ira Yarborough.

[1] Due to publishing lag time, the character saw print first in the Superman daily comic strip by writer Whitney Ellsworth and artist Wayne Boring.

[2] In most of Mxyzptlk's appearances in DC Comics, he can be stopped only by tricking him into saying or spelling his own name backwards, which will return him to his home in the fifth dimension and keep him there for a minimum of 90 days.

[3] This limitation of the character was modified in the 1986 Crisis on Infinite Earths reboot, upon which Mxyzptlk changes his condition to leave to a new requirement each story, such as having Superman succeed in getting him to paint his own face blue.

In his first appearance, Mxyztplk wreaks havoc across Metropolis by using his powers to pull all manner of pranks, first pretending he got hit by a truck and killed, then increasing his weight when the ambulance gets there and waking up to shock them.

[6] His only weaknesses are that he cannot stand being ridiculed and if he says or spells his name backward, he is involuntarily sent back to his home dimension for a minimum of 90 days.

This was changed to a futuristic looking orange outfit with purple trim and white hair on the sides of his head in the mid-1950s, although the bowler hat remains adapted to the new color scheme.

Mxyzptlk ultimately loses the election, and, his mission accomplished, Superman returns to Earth by whispering "Le-Lak" (his Kryptonian birth name Kal-El backwards).

Much crueler than his ancestor, this version kills most of the Legion of Super-Heroes until Superboy tricks him into falling victim to the same "Kltpzyxm" weakness, reversing the effects of his magic.

Mister Mxyzptlk (appearing in darker colors and looking more sinister than in the past) explains that the problem with immortality is finding ways to spend the time.

Before attacking Superman, he reveals his true form, which is described by Lois Lane as having "height, width, depth, and a couple of other things".

He is killed when Superman sends him to the Phantom Zone at the same time that Mister Mxyzptlk begins an escape to the fifth dimension by saying his name backwards voluntarily, tearing him in two.

Despite having recognized that his foe was too dangerous to be stopped any other way, remorse over the killing prompts Superman to drain himself of his powers using gold kryptonite.

Mxyzptlk made it through the Crisis on Infinite Earths relatively unchanged, although the unpleasant nature of his pranks and the psychological effects they have on others is played up more, such as when he animated the Daily Planet building heedless of the occupants inside who were being violently thrown around with its movements.

His first appearance in this new continuity saw him initially adopting the guise of "Ben deRoy", a reality-warping mystery man resembling the Beyonder (the former name is an anagram of the latter), who was threatening the Marvel Universe around the same time.

After his first encounter with Lex Luthor taught him how to lie, Mxyzptlk began rigging his contests with false or misleading aspects to make his challenges greater.

This story also saw the first Post-Crisis appearance of Mxyzptlk's Earth-One girlfriend, Ms. Gsptlsnz (described as his "quinto-partner"; pronounced Giz-pit-lez-nez or "Gizbie" for short).

In 2001, DC published Bizarro Comics in which Mister Mxyzptlk fought an all-powerful entity named A who is conquering and wrecking dimensional worlds—including the 5th dimension—by use of toys and games.

In Young Justice #3, Peter David showed Mxyzptlk's origins as a serious-minded researcher, who travels through time, summoned by computer-based occultists.

He chooses to examine a Halloween party in Happy Harbor, focusing on the results of aging a portion of the teens and causing some of the others to frantically dance out of control.

However, those words led to a shift in time, creating an apocalyptic world everywhere but outside the building where the Halloween party is being held.

The imp is unable to remember what to do to break the chain of events that daily culminates with Superman being dragged back to Arkham Asylum by Bizarro.

[10] A year later, in Superman Secret Files and Origins 2004 (2004), he returns to his usual self, following a fellow imp in the fifth dimension combining the twins with the classic Mxyzptlk, resulting in his normal form and personality.

The incident features alternate universe versions of Superman, Batman, and Deathstroke the Terminator and implies much chaos that was not shown, such as the planet Mogo visiting Earth to reclaim an old land mass.

After the fallout of the events of Day of Vengeance (and, while not mentioned, the corruption of the fifth dimension as seen in JSA), the removal of magic from the Earth leaves Mxyzptlk nearly powerless, wandering the streets of Metropolis and unable to remember how to pronounce the inverse of his name to return him home.

Action Comics Annual #10 states that Mister Mxyzptlk was last seen 190 days ago and that his name is pronounced "Mix-Yez-Pittle-Ick" (as it was in the 1960s Superman CBS-TV cartoon show, mentioned previously).

[14] The instant of the murder of the king, committed with the Multispear - a hyper-weapon - reflected in the three-dimensional universe Superman inhabits as a lifelong struggle with the five-dimensional being.

His gullible nature makes it easy for Superman or other individuals to trick him into saying his name backwards, and he is overall a fun-loving prankster who prefers to use his power for childish mischief and light-hearted harassment rather than malicious destruction or torment.

In Action Comics Annual #10 (2007), "Superman's Top 10 Most Wanted" describes Mister Mxyzptlk and provides the pronunciation as Mix-yez-pittle-ik, exactly like the 1967 animated series.

It is fair to say that producers were free to interpret the name any way they wanted, just as they routinely changed other elements of comic lore to suit their various series.