Feltipern Trevagg
Concept artist Ron Cobb illustrated a number of alien designs during the development of the cantina sequence. In the margins of the illustrations were a number of biological notes, explaining the creature's native environment. A twin-horned scruffy-faced alien was described as being a "High Tundra" creature, and that became its default nickname on set.
Make up artist Laine Liska crafted the High Tundra mask and hands. The alien was to have been given the proper name of Dratun. It wasn't until the Tales of the Mos Eisley Cantina anthology in the mid-90s that this alien was identified as corrupt tax collector Feltipern Trevagg. His alien species, the Gotal, was established in 1989's Galaxy Guide 4: Alien Races.
M'iiyoom Onith
When we first saw Feltiperrn in the cantina, he was snuggling up to a beak-nosed alien who was giggling up a storm. Beauty is in the eye of the beholder, of course, but this comely alien was given the unflattering on-set nickname of Yam Nose.
The alien was to have the proper name of Yamnoss, but instead fell into obscurity. The alien mask was resurrected for Return of the Jedi, though that particular alien is barely visible on screen.
In 1995's Tales from the Mos Eisley Cantina, we learn that Yam Nose is really M'iiyoom Onith, whose name translates to "Nightlily." She's a tender young H'nemthe with a deadly secret that Feltiperrn finds out during a stolen moment of intimacy.
Leesub Sirln
One of the on-set aliens shot in England, Leesub Sirln was only identified as "Weird Girl" in the production notes. She didn't get her proper name until the first set of the Star Wars Customizable Card Game, which established her as a Qiraash. A production photo of this character has her standing in front of the Millennium Falcon, suggesting the proximity of both the docking bay and cantina stages.
Solomahal
This alien has always had a military leaning. During shooting, it was known simply as "The Colonel," though another nickname was "the Hare Mouse." Seen both in the cantina and wandering the alleys of Mos Eisley, the Colonel had a very rotund build. Its original proper name was going to be Ownellco, but it went without a moniker until the Customizable Card Game established him as Solomahal. According to the lore printed on the card, Solomahal was a veteran of the Clone Wars. He most likely achieved the rank of Colonel.
The Saurins
There are at least two thirsty reptilian bipeds at the bar in A New Hope. On set, they were simply known as "Crockers" or "Gila-Men," but one of them was to have been given the proper name of "Gilaass." It wasn't until 1995 that they were given proper species name of Saurins, and individual names of Sai'torr and Hrchek Kal Fas.
Nabrun Leids
Turned into an action figure by Hasbro, the four-armed Nabrun Leids was called the Plutonian on set. Though Leids is a male, the slight build and production photography revealed the extra playing him to be a female. The alien's long, cone-like head prompted its other nickname, Squid Head, which predated the Quarren nickname by several years. This nickname became the source of its intended proper name of Quidultii, which was forgotten for years. The name Nabrun Leids came from the Customizable Card Game.
Takeel
Most fans know Snaggletooth from the vintage action figure made by Kenner. The legendary "Blue Snaggletooth" came about when Kenner didn't have adequate reference photography to design the figure of the alien, so the sculptors guessed at its body shape and wardrobe. The result was a Snaggletooth that was too tall, too blue, and a prized collector's item. Kenner corrected the alien by giving him a red jumpsuit and a shorter build, but even that particular Snaggletooth can't be found in A New Hope.
The Customizable Card Game gave the dopey-looking alien seen sitting next to Han and Chewie's booth the proper nameof Takeel. His species name, Snivvian, was developed around the same time by the roleplaying game. In the late 70s, the proper name "Tooggle" was set aside for this alien, though it went unused.
The mask was re-used for "The Star Wars Holiday Special", for a character wearing a red-and-black jumpsuit not used in the original film. It is this character that the action figure Snaggletooth is meant to represent. The Holiday Special established his name as Zutmore, which later became Zutton.
Greedo
Greedo was the only cantina alien whose name was actually spoken in the film. There were several Greedo-type aliens in the cantina and Mos Eisley scenes, all dressed identically. Production notes nicknamed Greedo's alien species "Martians," since the bug-eyed green-skinned suction cup-fingered alien fit many a Martian cliché. That name would never do for Star Wars, which is set in a distant galaxy with no Mars.
A 1978 memo established Greedo as one of the Graffties, a species of bipeds whose name may be a corruption of American Graffiti, in reference to Lucasfilm's other big hit of the era. In 1989, that name had been forgotten, and Galaxy Guide 1 established Greedo as a Rodian. Since then, "Rodian" has been adopted not only by the expanded universe, but also the production team that often uses the correct alien name in indentifying the many Rodian extras seen in the prequels.
Dannik Jerriko
Sometimes a cigar-smoker is just a cigar-smoker, and sometimes a background extra is a gateway to gothic horror fiction. The perfect example of an alien that's more than meets the eye, this simple extra identified only as "smoker" has gone on to have an elaborate, high-concept, and macabre backstory. The extra playing the smoker wore simple make-up to modify his features. There appears to be no attempt at naming this alien back in the 70s. Perhaps his hookah-habit prevented him from being an action figure -- a child's play thing dedicated to a smoker would probably have raised a few parental eyebrows.
Tales from the Mos Eisley Cantina reveals that the smoker is Dannik Jerriko, a centuries-old vampire with a dark and twisted past, who uses jagged proboscii concealed in cheek-pouches to drain the life from his unsuspecting victims.
