(covers information from several alternate timelines)
Morn was a male Lurian courier of the 24th century. He owned a shipping business that specialized in the transport of various mundane cargos. Morn gained a reputation while living on Deep Space 9 of being social and highly talkative, and he enjoyed a wide variety of alcoholic beverages as a frequent patron of Quark's and his best customer. (DS9: "Who Mourns for Morn?")
Lissepian Mother's Day Heist
Morn was one of five thieves who stole 1,000 bricks of gold-pressed latinum from the Central Bank of Lissepia in the Lissepian Mother's Day Heist of 2365. Morn somehow extracted the latinum from the bricks, then deposited the gold in the Bank of Bolias and stored the liquid latinum in his second stomach, causing most of his hair to fall out. (DS9: "Who Mourns for Morn?")
Life on Deep Space 9
The first time Morn walked into Quark's was around 2364, a time when he still had his hair. Quark thought he was just another customer passing through, when he sat down in what would soon be known as "his stool". Little did Quark know he would become such an important figure in his life, and to his bar. (DS9: "Who Mourns for Morn?")
After the Cardassians retreated from Bajor in 2369, Morn remained on Deep Space 9, which was then under Federation control. Morn spent most of his time at Quark's, becoming his most reliable customer and occasional business partner (notably in an attempt to setup an illegal Cardassian vole fighting ring; he was discovered painting numbers on the voles, and the operation was halted). (DS9: "Through the Looking Glass", "Emissary") Morn, while walking on the upper level of the Promenade in 2369, viewed Lursa and B'Etor arriving on Deep Space 9. (DS9: "Past Prologue") In 2370, with his freighter rendered inoperable during a warp core retrofit, Morn was seen evacuating the space station on the last available runabout, the USS Ganges, during a short-lived Bajoran coup. (DS9: "The Siege") In 2371, Morn sat near Tom Paris in Quark's and watched as Quark tried to scam Ensign Harry Kim into buying worthless Lobi crystals, which Quark said he had obtained from a strange creature called a "Morn". (VOY: "Caretaker")
Odo saved Morn from becoming a victim of illegal search and seizure by a belligerent Klingon posse on the Promenade, who asked Morn "…what he was doing so far away from the Ionite Nebula." (DS9: "The Way of the Warrior") Quark even let Morn run the bar temporarily while he was on a trip to Earth in 2372. (DS9: "Little Green Men")
In the weeks leading up to the Dominion War, Morn went berserk after hearing Quark predict the coming doom. He hit Quark with a barstool, and ran out of the bar and through the Promenade, screaming, "We're all doomed!" He then ran into the Bajoran shrine, stark naked, and began crying to the Prophets for protection. (DS9: "Blaze of Glory")
During the Dominion's control of Terok Nor, Morn took a trip to see his mother on her birthday, and brought an encoded message to Captain Benjamin Sisko from the resistance forces on the station, containing vital information about the Cardassians' timetable for disabling the minefield blocking the Bajoran wormhole from the Dominion's forces in the Gamma Quadrant. When Admiral Ross questioned whether the message was reliable, Sisko responded that he had known Morn for five years, and trusted him. Morn's actions spurred the Federation to launch Operation Return, thereby saving the Alpha Quadrant. (DS9: "Favor the Bold")
Morn attended the pre-wedding party thrown by Jadzia Dax in her quarters. He almost got into a fight with a Bolian, but the two managed to work things out. He eventually passed out behind the couch, leaving the following morning with an obvious hangover. (DS9: "You Are Cordially Invited")
The previous time Morn went away, Quark's sales dropped almost five percent. So, while he was gone, Quark created a hologram of the Lurian because his bar was incomplete without him. People loved Morn, and he felt that he was a mascot – everyone who came into the bar expected to see him, and if they didn't, it didn't feel like home, which wasn't good for Quark's business.
After a period of over two weeks, the beets Morn had left in the cargo bay began to rot, prompting Odo to seek him out in Quark's and ask that he remove them from the cargo bay. At the time, however, Morn was gone, and Quark had placed the hologram of the Lurian at "his stool", temporarily fooling Odo, to Quark's delight.
Moments later, Quark got word that Morn's cargo ship had been caught in an ion storm, where he had died. Following Morn's memorial, Quark learned from Benjamin Sisko, who unsealed Morn's will, that everything of Morn's was left to Quark: four cargo containers of beets, a mud bath "bed", a painting of a matador, and one-thousand bricks of gold-pressed latinum (in assay office locker 137).
It was later determined that Morn had faked his own death, after the statute of limitations ran out against the Lissepian Mother's Day Heist, in order to throw his fellow thieves off his trail. In return for Quark's assistance in getting the four other thieves off of his back, he offered Quark a quantity of the latinum that he had hidden in his second stomach. (DS9: "Who Mourns for Morn?")
Although he owned his own ship, Morn kept his quarters aboard Deep Space 9. His quarters were exceptionally spartan, containing a "hot tub" of mud, where he slept, and a painting of a matador. (DS9: "In the Cards", "Who Mourns for Morn?")
Morn was quite the ladies' man, and was often seen with a beautiful woman by his side. Morn once asked out Starfleet officer Jadzia Dax, who declined. She did say she thought he was cute, (DS9: "Progress") and, prior to 2372, later admitted that she used to have a little crush on him. As she explained it, however, he wasn't interested. (DS9: "Who Mourns for Morn?") Morn was attracted to several other females aboard the station and was frequently seen flirting with some, such as a Bajoran woman who received a hand kiss from him (DS9: "The Forsaken"), as well as a female Kobheerian (DS9: "Dramatis Personae"), and a Human Starfleet crewman, to whom he gave a flower in exchange for a kiss on the cheek, before walking away arm-in-arm. (DS9: "Let He Who Is Without Sin...")
Morn also enjoyed playing dabo, but couldn't get the hang of darts. (DS9: "Accession") He and Worf frequently sparred, having weekly combat in the holosuite. Worf thought that he was an excellent sparring partner. (DS9: "Who Mourns for Morn?")
In an alternate future, Morn attended the memorial service for Benjamin Sisko on the Promenade. He also ran Quark's in 2405, with the station under Klingon control. In 2422, he still ran the bar, which was named Morn's. Julian Bashir mentioned that Dax, Nog, and Jake Sisko could visit Morn's for a drink. (DS9: "The Visitor")
- "Emissary" (Season One)
- "A Man Alone"
- "Past Prologue"
- "Captive Pursuit"
- "The Passenger"
- "Move Along Home"
- "The Nagus"
- "Battle Lines"
- "The Storyteller"
- "If Wishes Were Horses"
- "The Forsaken"
- "Dramatis Personae"
- "In the Hands of the Prophets"
- "The Siege" (Season Two)
- "Rules of Acquisition"
- "Necessary Evil"
- "The Alternate"
- "Playing God"
- "Profit and Loss"
- "The Wire"
- "The Jem'Hadar"
- "The House of Quark" (Season Three)
- "Prophet Motive"
- "Family Business"
- "The Way of the Warrior" (Season Four)
- "The Visitor"
- "Little Green Men"
- "Starship Down"
- "Sons of Mogh"
- "Bar Association"
- "Rules of Engagement"
- "Body Parts"
- "Apocalypse Rising" (Season Five)
- "Looking for par'Mach in All the Wrong Places"
- "Trials and Tribble-ations"
- "The Assignment"
- "Let He Who Is Without Sin..."
- "In Purgatory's Shadow"
- "Doctor Bashir, I Presume"
- "A Simple Investigation"
- "Business as Usual"
- "Ferengi Love Songs"
- "Empok Nor"
- "In the Cards"
- "Call to Arms"
- "A Time to Stand" (Season Six)
- "Behind the Lines"
- "Favor the Bold"
- "You Are Cordially Invited"
- "Statistical Probabilities"
- "The Magnificent Ferengi"
- "Who Mourns for Morn?"
- "One Little Ship"
- "Wrongs Darker Than Death or Night"
- "His Way"
- "The Reckoning"
- "Profit and Lace"
- "Time's Orphan"
- "The Sound of Her Voice"
- "Tears of the Prophets"
- "Image in the Sand" (Season Seven)
- "Take Me Out to the Holosuite"
- "Once More Unto the Breach"
- "The Emperor's New Cloak"
- "Field of Fire"
- "Badda-Bing, Badda-Bang"
- "The Dogs of War"
- "What You Leave Behind"
- TNG: "Birthright, Part I"
- VOY: "Caretaker"
Morn was played by actor Mark Allen Shepherd. However, Ira Steven Behr once joked, "Actually, I play Morn. Marc Shephard is just an actor I've hired to confuse the fans at conventions… but don't tell anyone… It's a secret…" Behr also referred to the character as "our favorite barfly." (AOL chat, 1997)
The character of Morn was, essentially, something of a gag that the program's producers were playing on just about everyone else. Though other characters repeatedly referred to him as being talkative, social, and excitable, Morn was never actually shown doing anything much other than imbibing, and quietly at that, at Quark's bar.
Before the series was aired, Morn was simply known by staff as "the Grinch". Mark Allen Shepherd almost did not become Morn. Despite being hired for the role, the production crew accidentally left him off the calling list when they began filming DS9 series premiere "Emissary". By what Shepherd claims was intuition, he decided one day to wander onto the Paramount lot and see what was going on. Coincidentally that very day, Morn was to be filmed, so Shepherd ended up making his first appearance as Morn in "Emissary". The actor's contribution impressed the producers so much that Morn was made a recurring character. (The Making of Star Trek: Deep Space Nine)
"Morn" is an anagram for Norm, the barfly played by George Wendt in the TV show Cheers. (Star Trek Encyclopedia (4th ed., vol. 2, p. 54)) Morn was first identified by name in "Vortex" (although his name had previously been used in the scripts for "Dax" and "The Nagus").
It is possible that Morn was androgynous since Odo, while making an announcement to passers-by on the Promenade of Deep Space 9 in "If Wishes Were Horses", says "Ladies and gentlemen (noticing Morn walking by) … and all androgynous species…" It is reasonable to assume Odo was making a joke at Morn's expense, though given the gravity of the situation, he could have been serious. The former seems to be true since Morn is referred to as male in subsequent episodes.
According to Mark Allen Shepherd, over the years a number of episodes were written during which Morn spoke various snippets of dialogue, but his lines were always removed by the time the script was being shot. In one particular example, Morn was to come down the spiral staircase in Quark's wearing a tuxedo, having been in the holosuite using the Julian Bashir, Secret Agent holoprogram. Quark was mixing a drink for Morn at the bar, and Morn looked over at him and said, "Shaken, not stirred." This scene remained through a number of script rewrites, to the point that Shepherd (in full Morn makeup) was actually fitted for a tuxedo, but at the last minute, the scene was removed. ("Morn Speaks", DS9 Season 7 DVD, Special Features)
Shepherd also added: "There have been numerous scripts where they originally had Morn speaking. One such script had to do with the alternate universe. Unfortunately, they always got written out". 
Aside from Mark Allen Shepherd, Dennis Madalone is the only stunt performer or actor to have portrayed Morn. In "Looking for par'Mach in All the Wrong Places", there is one stunt scene in which Morn is thrown from his bar stool by Worf, a stunt that was performed by Madalone.
During the fifth season, Ronald D. Moore, in an AOL chat, gave a summary of what was going on in the show, ending by joking that Morn had become President of the Federation. (AOL chat, 1997) Moore later declined to comment on allegations that Morn had accepted illegal campaign contributions from the Ferengi or the Romulans, as a special counsel investigation on the matter was underway. (AOL chat, 1997)
In the episode "Who Mourns for Morn?", Shepherd, without the Morn makeup, briefly appeared as the Bajoran customer whom Quark asks to fill Morn's seat. In relation to the character's namesake, the manner in which Dax shouts Morn's name upon seeing the hologram at Quark's, in "Who Mourns for Morn?", is reminiscent of the greeting Norm usually received as soon as he walked into Cheers. Morn was first identified by species in "Who Mourns for Morn?".
In an ultimately unused scene from the first draft script of "The Changing Face of Evil", Morn was applauded and took a bow in Quark's, having read a poem, then made a quick exit from the bar. Kira Nerys and Julian Bashir were amazed by the poetry recital Morn had delivered. Bashir and Ezri Dax, who had just missed the event, assumed Morn had written the poem, though it was actually "Howl" by Allen Ginsberg, as Kira pointed out. Nonetheless, Ezri Dax admitted the incident showed there was more to Morn than they'd expected.
Although Morn does not feature in the next episode, "When It Rains...", he was to have appeared at the start of a scene from that episode's first draft script. In it, he and Ezri Dax were on the Promenade, outside the infirmary, and Morn had apparently just given Dax some relationship advice regarding her feelings for Bashir, as Ezri stated, "You're right, I should just go in there and tell him how I feel. Thanks, Morn." He nodded in response, and Ezri, now with a determined expression on her face, then left him.
With ninety-three appearances, Morn appeared in more episodes of Deep Space Nine than Jake Sisko (Cirroc Lofton), a regular cast member with only seventy-one appearances.
Morn never spoke a single word throughout all of Deep Space Nine, with the only time he was ever depicted vocalizing being his laugh in the episode "The Nagus". In the German version of the episode "The Jem'Hadar", however, he does speak; he is just about to tell Quark what has been troubling him when Quark simply walks away. Resigned, Morn mutters, "Dann nicht…" (roughly meaning "So much for that…"). These words are not uttered in the original English version.
Along with Quark, Q, and Evek, Morn is one of only four characters to appear in all of the first three Star Trek series based in the 24th century: Star Trek: The Next Generation, Star Trek: Deep Space Nine, and Star Trek: Voyager.
In the short story "Mirror Eyes", from the anthology Tales of the Dominion War, the narrator, a Romulan Tal Shiar agent working undercover aboard DS9, identifies Morn as the only inhabitant of the station with whom she feels "an intellectual kinship."
In the video game Star Trek: Deep Space Nine - Crossroads of Time, Morn can be found on the upper level at Quark's. He is the only character in the game that doesn't talk.
In the video game Star Trek: Deep Space Nine - The Fallen, Morn makes several appearances on the Promenade between missions.
In Star Trek Online, Morn can still be found in Quark's bar.