The Pakleds were a humanoid species in contact with the Federation by the 2360s. To the casual observer the Pakleds appeared to be intellectually challenged, especially in their verbal skills. However, despite the marked lack of intellect they proved to be far more cunning than they appeared, and used their innocuous appearance to deceive other races.
The Pakleds' own technology was significantly less advanced than that of many other spacefaring races. According to Data in 2365, it remained "a genuine curiosity how they ever mastered the rudiments of space travel." They were driven by their unwillingness to develop technological knowledge on their own, desiring to instantly gain the power that other cultures enjoyed. They therefore tried to acquire technology from other species, generally by theft. (TNG: "Samaritan Snare")
In 2365, a Pakled transport named Mondor sent out a Mayday in the Rhomboid Dronegar sector 006 in order to lure in other ships whose technology could then be stolen. They were offered assistance by the USS Enterprise-D, who lent the Pakleds their chief engineer, Geordi La Forge, to help fix their ship. The Pakleds kidnapped La Forge, but eventually returned him after the Enterprise demonstrated its "force" with a harmless pyrotechnic display involving the Bussard collectors. (TNG: "Samaritan Snare")
List of PakledsEdit
Background information Edit
The script for "Samaritan Snare" describes the Pakleds as, "slothful, droopy-eyed humanoids", with, "typically wistful Pakled hypoplastic speech, almost a sense of hopeful longing in their every word"  And in the original script for Star Trek Nemesis, the android B-4 is taken from his homeworld by the Pakleds, whom he calls "fat". He is ultimately deemed useless and is traded to the Bolians. 
The Pakleds were introduced as a race of aliens intended to appear slow-witted and harmless, incapable of creating their own technology, but in reality were a sharp and nefarious race who would steal anything they wished. The makeup department had to bear this in mind when designing the Pakled appearance. To aid them in this, the casting department hired portly actors whose expressions were naturally benign, in order to convey a sense of innocence. The makeup itself consisted of appliances for the foreheads, cheeks, and a pointed lower lip. The makeup department also came up with a set of eyebrows that went up to the center of their foreheads, intended to project a sense of helplessness about their situation. For the mouth, a set of double-size teeth was used. (Star Trek: Aliens & Artifacts, pp.111-113)
Of their appearance in "Samaritan Snare", Director Les Landau recalled, "What I had to deal with was a race of people who appeared to be dimwitted and unattractive, but yet had a need for things to make themselves sufficient. I didn't want them to appear silly, foolish or unrealistic, or rather unbelievable, so it was a constant self-conscious awareness to keep them threatening yet simple." (The Official Star Trek: The Next Generation Magazine Vol. 21, p. 42)
Though their only major appearance was in "Samaritan Snare", the Pakled went on to appear in the background of several Deep Space Nine episodes, and were mentioned in "Brothers" as rescuing Data's brother, Lore. A person wearing a Pakled costume can be seen in the bar on Ronara Prime in "Preemptive Strike", however, he lacks the unique Pakled facial features.
The Pakleds were briefly considered to feature as main antagonists in DS9: "One Little Ship", when the episode was in pre-production, by which time it was too late to make such a drastic change to the episode. "During prep I started saying, 'We should have used someone like the Pakleds from TNG,'" offered René Echevarria. This idea was dismissed by Executive Producer Ira Steven Behr in favor of Harcourt Mudd instead being used as the villain, despite neither of them ultimately being used. (Star Trek: Deep Space Nine Companion, p. 531)
In the shooting script for Star Trek Nemesis, B-4 revealed in a lengthy speech that he was originally rescued from Omicron Theta by the Pakleds, but that they dumped him in a junkyard after finding his intellect uselessly limited even compared to their own. 
"PACK-led" was the pronunciation of this species' name from the script pronunciation guide for the "Samaritan Snare". 
In the Strange New Worlds 10 short story "A Dish Served Cold", set in 2373, a Borg cube en route to Sector 001 encounters a Pakled freighter, but the Collective considers them unintelligent and an inefficient use of resources to assimilate. However, they are later assimilated when the Borg need extra reinforcements in their battle with Starfleet forces in Earth orbit. They are designated as Species 95012.
In Star Trek Online, Pakleds are a playable race for Starfleet, which may indicate they have become a member of the Federation. Visually, the Pakleds are a lot less bulky than in Star Trek canon (though their appearance can be modified in the character customization editor).
Pakleds are also one of the races that can be discovered in the video game Star Trek: The Next Generation - Birth of the Federation.