||An animal native to the planet Andoria. Zabathus could be ridden much as Earth horses could. A simulation of a Zabathu was one of the options available for riding on the holodecks of the Enterprise-D1
||Delta Quadrant civilisation eradicated by the Krenim in an alternate timeline2
||Year of Hell, Part 1
||The Zakdorn are considered master strategists, a reputation so fearsome that nobody dares to attack them.3
||The Zaldan have webbed fingers and are infuriated by courtsey, which they believe is a form of dishonesty.4
||Coming of Age
||In 2366 the Enterprise-D located a small single-person crashed spacecraft on the surface of an uninhabited. The badly wounded pilot had lost all memory of his part life as a result of his injuries - he could not even remember his own name. Although he responded to treatment by Dr. Crusher, the man exhibited several unusual traits - his cells were apparently mutating at an ever-accelerating rate, and his body was able to produce strange energy discharges. None of this seemed to be particularly harmful to the man, who the crew dubbed "John Doe", and he even demonstrated an ability to heal injuries with these energy pulses.
Analysis of parts from John's crashed ship provided some clues as to his origins, and the Enterprise began to investigate this. Eventually they came across a Zalkonian ship - a species previously unknown to the Federation. The Zalkonian commander, Sunad, claimed that John was a dangerous criminal and demanded that he be returned. John, on the other hand, claimed that he was beginning to remember enough about his past to know that Sunad was a dangerous and dishonest character not to be trusted.
The standoff ended when Sunad used an unknown technology to incapacitate the crew of the Enterprise-D in an attempt to retrieve John. John was able to use his growing energy abilities to prevent the attack. In the process he regained his memory.
John explained that individuals amongst his people had been undergoing this transformation for some time now. The authorities, fearful of something which they did not understand, had labeled the changes as a dangerous disease and had "destroyed" those exhibiting the signs. John and some others had chosen to believe that the changes were not harmful, and had escaped their home world in order to allow the process to run its course. He completed the transformation on the bridge of the Enterprise-D, becoming a being of pure energy. With his greatly increased abilities John assured Captain Picard that he would now be able to return to his home world and show the remainder of his people the truth, allowing those who wished to be transformed themselves.
The Federation has had considerable experience with non-corporeal species, and this seems to be an evolutionary stage reached by many life forms in the fullness of time. Notable examples include the Organians discovered by Captain Kirk. This incident was a rare chance to see the transformation from the physical state to the energy state actually in progress.5
||Species native to the Ferengi planet Lappa IV6
||Menage a Troi
||Members of the United Federation of Planets, the Zaranites are from the planet Zaran II.7 A Zaranite was present in the Federation Council chamber in 2285 during the Cetacean probe crisis.8
||Star Trek IV Sourcebook Update
||The Zeons where pesicuted by the Ekosians.9
||Patterns of Force
||A member of this species served on board the USS Enterprise in 2293. The species are notable for their extremely large feet, which make it impossible to wear shoes that are suitable for Humans.11
||Novelization of Star Trek VI : The Undiscovered Country
||Non-corporeal species whoattacked the Federation databank at Memory Alpha. 12
||The Lights of Zetar
||Civilisation who requested some information on a smuggling ring from DS913
||Humanoid civilisation noted for facial tattooing. A Zibalian once attempted to kidnap Data.14
||The Most Toys
||Life form which is known to lay eggs. Data attempted to paint Zylo eggs as a test of his creativity.15