PHYLOSIAN WILDLIFE

Apart from the sentient phylosians, the ecosphere of the planet Phylos has developed several other mobile plant lifeforms. Among them, the Retlaw, the large predatory Swooper, both using their roots for nourrishment and locomotion.
Source: Star Trek

PHYLOSIANS

Planet of Origin: Phylos, on the edge of the galaxy
The Phylosians are a sentient species of mobile plants who developed a technologically advanced civilization. They have a naturaly long life span which they extended with their science. While they had not yet ventured much outside their hoemworld, they had developped theoretical knowledge of interstellar travel and had even devised a plan to build a fleet of large military ships to ensure peace in their interstellar neighborhood. Exposure to a staphylococcus strain of bacteria brought by a human explorer stopped their effoert and wiped out most of them in the 22nd century. By cloning himself, the explorer was able to cure the phylosians over the course of the next century.
Source: Star Trek the animated series "The Infinite Vulcan"

EDOSIANS / EDOANS / TRIEXIANS

Planet of Origin: Edos in the Triangulum constellation on the rim of the galaxy.
Edosians are a tripodal species, with three arms, three legs and three fingers on each hand.
The Edosians are a peaceful,long-lived species worshipping many gods who have developed a class-less society in whihc all are considered equals. Edos has never been involved in a war. its technology is as advanced as Earth's. The architectural style of its cities is strictly functional rather than esthetically pleasing.
In the 23rd century, they were allies of the Federation of Planets. Contact was already established with Earth or an affiliated species in the mid-22nd century (as Knowledge of the Edosian suckerfish among Humans would suggest, as mentioned in Star Trek: Enterprise)
Source: Star Trek the Animated series, Lincoln Enterprises Star Trek Catalog Number 5

SATICONS

Saticons are a mysterious faceless humanoid entities of unknown origin. They travel in groups of three, wear long, black garments, and bowler hats. The lead Saticon had a sun-like icon on the front of his hat.
Saticons can travel from planet to planet by means yet unknown and have access to highly advanced technological knowledge. When seen, they always seem to be after an object of power with which they want to accomplish some terrible feat.
Source: Lost in Space (Wreck of the Robot, The Galaxy Gift)

BUBBLE CREATURES

The bubble creatures are a non-humanoid spacefaring species resembling a gnarled, melting lump of greenish-brown flesh, with several pulsating multi-faceted 'bubbles' of various colors protruding from various spots on their body. They communicate by electric arcing on the surface of their bubbles.
Source: Lost in Space "The Derelict", "Prisonners in space"

EURYTHMANS

Planet of Origin: Eurythma

The Eurythmans are a humanoid species looking much like humans which developped their culture entirely around music and speak in a constant, lilting sing-song manner. Among their achievements is the ability to use sound vibration for varied uses, including healing and a three-part harmony of incredible destructive power which was once used to blast out of the sky a comet in collision course with the planet.

Source: The Transformers the Animated Series

SKUXXOIDS

Skuxxoids are an intelligent reptilian species that often sell their services to the highest bidder as mercenaries for credits. They have scaly skin and stand from 4 to 5 meters high. Skuxxoids have been known to be hired by Quintessons ("Five Faces of Darkness, Part 1 & 2) and Cybertornian Dececpticons (Chaos, Starscream's Ghost, Grimlock's New Brain). They tend to use large asteroid ships as their primary mode of transport and it is quite probable that most of their technological advancement came from scavenging or trading their serivice against tehcnological upgrades.
Source: The Transformers animated series

A PICTURE OF THE AMBASSADOR

SEA HARES

Sea hares were named by the colonists after their face's uncanny ressemblance to Earth's hares.

PROGENITORS / ANCIENT HUMANOIDS

The ancient humanoids are among the oldest planetbound sentient species to evolve in the Milky Way Galaxy some 4.5 billion years ago. They seeded the primordial environments of many planets with a DNA code that would direct the evolution of life towards a form similar to their own. Earth, Indri VIII, Loren III, Ruah IV and Vilmor II are known to have been directly seeded but other species that likely originated from seeded primordial seas included Klingons, Vulcans, and Cardassians, and probably most humanoid species.
Rumors have it that some of the fragments of DNA also contained parts of a computer program designed to display a holographic message from an ancient humanoid explaining its race and their actions. It was hoped that their descendant species would come together in the spirit of cooperation in order to assemble the program. This message was supposedly discovered in the 24th century.
Note: In Doctor Who, The Timelords are said to have had a similar plans, establishing a morphic field so that the species that would develop on other planets would have a physiology similar to their own.
Source: Star Trek the Next Generation "The Chase"

VAMPIRE CLOUD / DIKIRONIUM CLOUD CREATURE

The dikironium cloud creature, also known as the "vampire cloud", is an intelligent, predatory, gaseous lifeform that feeds by forcibly extracting the corpuscles of iron-based blood of its preys. It exists in a borderline state between matter and energy, with elements of both and utilizes gravity fields for propulsion, especially for traveling through space at faster-than-light speeds. It is also able to "throw itself out of time-sync", enabling it to be "elsewhere" while being hit by energy weapons and can also temporarily change its molecular composition into other elements to evade being scanned. In a atmospheric envrionment, it gives off a sickly-sweet odor, best likened to honey. It has a big dislike for copper.
The only specimen of that species ever encountered creature attacked the spaceship USS Farragut in 2257, killing most of its 200 crewmen and destroyed eleven years later with a massive antimatter explosion and it remains unknown if the creature is unique or a specimen of a species.
Source: Star Trek The Original Series "Obsession"
Thanks: Thanks to the Memory Alpha Wiki for the pictures

CRISTALLINE ENTITY

The Crystalline Entity is a spaceborne crystalline living structure that resembled a large snowflake. It has warp speed travel capability, formidable size, and functioned as a giant electromagnetic collector and needed constant power, converting organic matter into energy on a scale large enough to consume all life on a planet.
Source: Star Trek the Next Generation "Datalore", "Silicon Avatar"

STAR-JELLIES / SPACEBORN ENTITIES / SKYMOUNTS

The Star-Jellies are large intelligent space dwelling cosmozoan lifeformes ressembling large luminescent jellyfish. Although they are primarly spacebound, they able to survive both in the vacuum of space and on a telluric type planet. They are capable of manipulating energy to create the effects of replicators and transporters, which allows them to transform themselves into virtually antyhing and even to separate transformed parts of itself from its being and to warp space to attain interstellar speed.
When flying at warp speed, Starjellies usually retract their tendrils which gives them a roughly saucer shape, about a kilometer in diameter.
Two such beings were witnessed in 2364, in the Deneb system but left for destination unknown.
It has been rumored that some species might have used such creatures as spaceships
Source: Star Trek The Next Generation, "Encounter at Farpoint"

LACTRANS

Planet of Origin: Lactra VII, Milky Way
The Lactrans are a civilization of highly advanced telepathic 30-meter-long slug-like lifeforms.
Source : Star Trek the Animated Series: "The Eye of the Beholder"

NEURAL PARASITES

The species refered to as "Neural Parasites" resembles a crawling insects that enters a host organism, attaching itself near the central nervous system - on the spine near the brain, in the case of a human, with a small spine-like protrusion visible at the base of the neck to allow breathing. The parasites are highly intelligent and are able to habe appreciation of the cultures they are parasiting. A host inhabited by a parasite will display increased physical strength and endurance.
The parasites are connected to a mother organism, a larger creature likewise capable of inhabiting a host. The death of this creature seems to result in the deaths of all progeny. (TNG: "Conspiracy")
They attempted to infiltrate Earth in 2364, by physically infiltrating high-ranking officials within the organization but theuir attempt was thwarted. However, the mother organism had sent a signal toward deep space, wether this was a call for help or a warning remains unknown.
Notes: It has been rumored that the parasites might have been agents of the Borg collective.
(This was the episode's writers original intent. However, due to the 1986 Writers' Strike as well as budget cuts, the connection between the Borg and the parasites was never established. (Star Trek: The Next Generation Companion)
The neural parasites are in many ways similar to the Goa'uld, a race of malevolent, power-hungry parasites from TV series Stargate SG1.
Source: (Star Trek The Next Generation: "Conspiracy"

SHELIAK

Planet of Origin: A planet in the Shelia / Beta Lyrae star system (ca. 882 lightyears from Earth)
The Sheliak are a reculsive species that developped a space faring society as of the 23rd century. Althought they travel through space and have colonised other planetss, they try to avoid contact with other species whenever possible.
Not much is known about the Sheliak social system but colonists refer to themselves as "the Membership" and have a governing body called "the Corporate".
Unlike most humanoids, the Sheliak prefer to exist in an environment that is the same temperature as their bodies. (TNG: "Starship Mine")
Source: Star Trek The nExt Generation (TNG: "Starship Mine") (TNG: "The Ensigns of Command" for reference to homeworld)
Note: The Thrakallans seen in Babylon 5 also come from the Beta Lyrae system.

MEDUSANS / VISALAYANS

Planet of Origin: Medusa (Visalayan), orbiting the G8 star Xi Hydrae, 129 light years from Earth.
The Medusans are an highly evolved peaceful telepathic non-corporeal species. The visual impression they leave upon those they meet is so utterly hideous that the sight of a Medusan renders most humanoid lifeform mad. Some species are known be able to withstand their sight but only through the use of a specially filtered visor. For these reasons, Medusans usually use an opaque carrier pod when interacting with other species. The Medusans was a member of the Federation of Planetes in the twentietn century and had limited contact with some other species.
. (TOS: "Is There in Truth No Beauty?")
Source: Star Trek TOS: "Is There in Truth No Beauty?"

APPARITIONS

Not much is known about those eirie apparitions. They've been witnessed in spaceship graveyards, asteroid fields, planteray rings and other such places. They appaear to be humanoids wearing spacesuits and exhibiting luminous body parts where they're visible, with long tentacles like appendages growing out of them. Some specimen were identifiable as humans and other known space farign species, while otehr appeared clearly alien. They're always highly aggressive and have been known to hunt in pack or alone. They prefer ambush to all out attacks.
Legends talk about supernatural manifestations, but a popular explanations to the phenomenon is that of a parasite taking control of the bodies of space travellers, turning them in some kind of zombie under its control. As no specimen has been caught yet, the mystery remains.

PINK ENTITY

Planet of Origin: a windy and desertic planet 5000 light years from Earth, in the direction of the Pleiades.
The pink entity is a large soft mass covering a surface of about 6 meters in diameter by three meters high. While not humanoid, its shape is remotely reminiscent ofa huge couch potato.
The Pink entity has existed for several millions of years and has no memory of its beginning and cant recall any physical change, wether growth or deterioration in its physical mass.
It has powerful psychic powers and spends most of its time fishing telepathically for other telepathic entities with wich to communicate. It is collecting other people's mind, exchanging an image of its own mind with them. The entity has in its own mind images of the minds of thousands of alien. Being a solitary being, possibly to only of its kind, it does not do much with that wealth of knowledge and live a quite goal-less existence. It usually have a friendly attitude toward otehr sentient beings.
The entity lives in a construction sheltering it from the harsh weather conditions of its world. If he built it or how remains unknown.
The entity had contact with humanity during the first half of the third millenium through Shepherd Blaine, a telepath working for the Fishhook Corporation while psychically scanning distant worlds.
Source: Clifford D. Simak, Time is the Simplest Thing.

ARMADILLO CALAMARI

This aquatic creature attracts small preys with the luminous organs situated on its belly and shoulders. It catches them with its long prehensile tongue. Its tentacles can sometimes be of help for holding larger preys or searching the seabed for food. When threatened, it rolls on itself and lay on the ground so as to look like a big rock. It tends to hunt alone but can sometimes be seen in packs of up to 8 individuals.