Mudd androids
The androids of the planet Mudd originated in the Andromeda Galaxy. They were constructed by a humanoid species, known simply as the "makers", for the purpose of performing necessary service functions, freeing their makers to evolve a perfect social order. Large groups of androids were sent to establish outposts for various purposes. At one time, there were many such outposts of androids scattered throughout the stars, but when the sun of their homeworld went nova, the androids' "makers" slowly became extinct. By the later 2260s, there were only a few outposts remaining. On one of these outposts, located on a K type planet in the Milky Way Galaxy, the androids worked at adapting the planet for productive use. They had managed to build vast libraries, impressive medical research laboratories, and cutting-edge engineering shops until the slow march of time caused them to lose focus on their original purpose. The accidental arrival of the Human Harcourt Fenton Mudd sometime between 2266 and 2268 brought the androids a new, if misguided, purpose.

Organization 

By the 2260s, there were some 207,808 androids on what became the planet Mudd. They were led by a single coordinator named Norman, who utilized a central control complex to join them into a gigantic, highly intelligent hive mind. The androids were divided into groups of identical models each numbering up to five hundred units. Among these were the Herman series, the Oscar series, and many others. Constructed of a self-renewing plastic over a skeleton of beryllium-titanium alloy, none of the android bodies had ever worn out, but the estimated duration was 500,000 years. In addition to being very resilient, they were also exceptionally strong.

While the android collective brain is vast and formidable, it had a weakness in its inability to process logical paradoxes and irrational behavior.

The Mudd era 

When the planet was stumbled upon by fugitive Harry Mudd, the androids dubbed him Lord Mudd the First and made him their ruler. Serving Mudd with near-absolute loyalty, they nevertheless held him against his will. While ruler and prisoner of the android population, Mudd ordered the construction of an additional 2,501 androids, most of which were very attractive female models, including the Alice series, the Barbara series, the Maisie series, the Trudy series, and the Annabelle series. In addition, he commissioned a single android in the image of his estranged wife Stella, whom he could command to be silent at will to amuse himself.

Needing beings to serve, and being less than satisfied with Harry Mudd as the sole provider of purpose, the androids promised to allow him to leave if he would help them secure new specimens to serve. At Mudd's direction, Norman posed as a Starfleet officer and commandeered and sabotaged a Federation starship, the , and forced it to the planet Mudd. 

However, the androids' long observation of Harry Mudd caused them to draw certain negative conclusions about the Human race as a whole. Although realizing that Mudd was flawed even for a Human being, the androids nevertheless determined that the Human race was much too greedy and corruptible to have free run of the galaxy. They determined the best way to control Humanity's aggressive and inquisitive instincts was by serving them, until Humans became completely dependent on them, happy and controlled. For that reason, they decided to leave Mudd on the planet and leave on the Enterprise themselves in order to offer their "services" to Humankind. ()

The post-Mudd era 

Using a combination of irrational behavior and logical paradoxes, the androids were eventually overcome by the Enterprise crew with the assistance of Harry Mudd. With the androids incapacitated, it became possible for the Starfleet personnel to reprogram the androids to continue once again the project they had been sent to the planet to accomplish. In addition, the androids were to be left with custody of Harry Mudd, not as a sovereign ruler, but instead as a "first-class example of a Human failure", to be observed in order to avoid similar individuals in the future. In addition, at least 500 new androids based upon Harry Mudd's original Stella design,were commissioned by Starfleet Captain James T. Kirk, including its characteristic shrill and shrewish demeanor, but without any regard for Harry's command for it to "shut up".  ()

Series of Mudd androids 
According to Spock – aside from the six series seen and Norman, who was in a class by himself – there were "a whole plethora of series."