This is a list of alleged extraterrestrial beings, alleged interdimensional beings, and alleged cryptoterrestrial beings that have been reported in close encounters, either claimed or speculated to be associated with the purported phenomenon of unidentified flying objects (UFOs) (not to be confused with the meaning of the term "alien species" in the biological science of ecology).
Flatwoods monster The Flatwoods monster was alleged by witnesses to be a tall humanoid with a spade-shaped head. A common skeptical explanation has been a misidentified barn owl.Froglike Humanoids Harrison Bailey encounter Loveland Frog Rarely, witnesses have alleged encounters with amphibianlike humanoids. One recorded case involved a steel-worker named Harrison Bailey, who purportedly witnessed a UFO and claimed to have communicated with diminutive, bipedal frog men in 1951. Another famous case, though a UFO was not directly seen, involved alleged froglike humanoids ostensibly communicating with each other; one was reportedly holding a rod overhead that was emitting flashes or sparks. Skeptics have suggested such sightings were the misidentification of known fauna. "Giants" Mystery airship pilot, 1897 Meng Zhaoguo encounter Voronezh beings On rare occasion, alleged humanoids of prodigious scale have been reported. Modern accounts of giant humanoids at or in excess of include that of the Voronezh beings in 1989, and later the humanoids described by woodcutter Meng Zhaoguo in 1994. One notable early case was claimed to have occurred on 16 April 1897 during the "mystery airship" flap, wherein a purported being approximately nine and a half feet () tall was allegedly sighted in a landed craft, speaking in a melodic "bellowing"; however, historian and ufologist David M. Jacobs has suggested that some such accounts from this era may have instead been journalistic tongue-in-cheek pieces. Greys (also grays) Roswell incident Betty and Barney Hill Whitley Strieber Greys are often reported to be humanoids of small stature, usually tall, featuring large hairless heads, black almond-shaped eyes, nostrils without a nose, slits for mouths, no ears, and 3–4 fingers on each hand (including a thumb). Tall greys have also been reported. Greys have been the predominant extraterrestrial beings of alleged alien contact since the 1960s. Skeptics commonly suggest that such reports are the result of sleep paralysis. Hairy mammalian humanoids In rare instances, hairy "mammalian" humanoids have been described. Though some encounters have purportedly involved beings with batlike faces, Bigfoot-like sightings are also represented in reports. An unconventional paranormal theory speculates that Bigfoot is of non-terrestrial origin. At least in the case of Bigfoot sightings, skeptics have often proposed more earthly explanations altogether, such as the misidentification of bears standing on their hind legs. Hopkinsville goblins Kelly Green Men Accounts of the Hopkinsville goblins portrayed them as small, silvery humanoids with a "greenish-silver glow". A commonly proposed skeptical explanation is that they were misidentified great horned owls. Humanoids alleged by Carl Higdon "Ausso One" Witness Carl Higdon alleged that his abductors were humanoids with strawlike hair, no eyebrows, no jaw, no visible ears, standing at about tall, and dressed in glossy black. They were notably sensitive to sunlight. The main individual described was characterized as a "hunter or explorer". The use of hypnosis to aid recall in this case has been called into question by skeptics. Humanoids alleged by Evelyn Wendt Dade City "flowers" Witness Evelyn Wendt reported that in 1924, when she was a child in Dade City, Florida, she looked on as "animated flowers with faces where the bud would be" departed an egg-shaped object. She indicated that they were robotlike and noted they were of a smaller stature than her. This account was also featured in the skeptical compendium UFOs & Alien Contact: Two Centuries of Mystery; in his book review, skeptic Robert Baker assumed that encounters with unknown beings (like those cited in the book) may have been attributable to varying psychological explanations. Humanoids alleged by Federico Ibáñez Landing at Turis Witness Federico Ibáñez allegedly encountered beings approximately tall draped in white, full-body garments resembling encapsulating chemical suits, wearing what appeared to be protruding eyewear on their heads. Skeptic Luís R. González and bibliographer Carlos González Gutiérrez have noted the similarity to humanoids from the then-recently released Star Wars. Skeptical researcher Vincente-Juan Ballester Olmos has likewise explored the notion that the encounter may have been a brief psychological phenomenon affected by pop culture influences, although admits that the witness ostensibly neither had any history of similar psychological phenomena nor particularly high awareness of the then-recent science fiction trend. Humanoids alleged by Kelly Cahill Witness Kelly Cahill alleged that her abductors were tall humanoids, dressed in dark hoods with glowing red eyes. Cahill further claimed that she perceived the intentions of the specific individuals she purportedly encountered as negative. Though it has been touted as a particularly noteworthy case due to the involvement of multiple and even ostensibly independent witnesses, the potential for the one-off event having a psychological explanation has been discussed. Humanoids with a blue complexion Blue men of Studham Common Uncommonly, beings with a blue complexion have been reported. One such report was made in Studham Common, where gnomelike, blue humanoids were allegedly sighted by children on the way to school in January 1967. Author Whitley Strieber, who purportedly had abduction experiences with greys, also claimed an alleged encounter with gnomelike, blue humanoids in the eighties. Like greys, skeptics suggest abduction reports of blue humanoids are the result of sleep paralysis. Humanoids with one eye "Cyclops" of the Sagrada Familia neighborhood An alleged cycloptic humanoid of ruddy complexion that purportedly stood at a height of over was claimed to have attempted to communicate with eyewitnesses in Belo Horizonte. Multiple cyclopes were reported in this alleged encounter. A documentary was released in 2022 about the incident titled Alien Cyclops: The Extraordinary Case of Sagrada Familia, according to which, the witnesses had maintained their testimony two years following the incident even as investigator Húlvio Brant Aleixo attempted to steer the follow-up interview into a more adversarial form of skeptical inquiry. The humanoids the witnesses reported were also referenced in The Field Guide to Extraterrestrials, in which author Patrick Huyghe's ostensibly admitted a certain degree of personal skepticism with regard to close encounters in the forward, opining that a psychological explanation might exist in general, which skeptic Robert Baker also touched upon in his book review thereof. Humanoids with "sweepers" A witness in Uden, Netherlands, claimed to have seen a metallic spherical object and also claimed to have looked on as unknown humanoids, in garments similar to white monastic habits, used unknown devices resembling sweepers. A similar encounter occurred in Vilvoorde, Belgium, with a being scaling a wall and ostensibly another similar encounter took place in Canada; skeptical explanations have included misidentified utility workers. Humanoids with winged forelimbs "Avians" Alleged encounters with humanoids of a generally avian appearance have also been rarely described, and have sometimes been broadly categorized with reports of humanoids with winged forelimbs in general, like those of chiropteran appearance. However, these classifications are of such a notable level of rarity that author Patrick Huyghe, who despite expressing a certain degree of skepticism about close encounters in general in the forward of his 1996 book The Field Guide to Extraterrestrials, admitted to only being able to find one such (chiropteran) example from Hythe, Kent while broadly compiling reports. Examples of avian humanoids have included the bird-beasts of Var, which were purportedly seen with a UFO, and also Mothman, which is sometimes speculated to have a non-terrestrial provenance. A chiropteran, or possibly quasi-pterosaurian, example lies in the Van Meter Visitor, which was implied by contemporary reports to be cryptoterrestrial. Humanoids with winged serpent (or crossed serpent) emblems Herbert Schirmer encounter William Herrmann encounter Filiberto Cardenas encounter On 3 December 1967, police officer Herbert Schirmer reported witnessing a UFO, claimed to have experienced missing time, and later underwent hypnosis. He ultimately described a group of humanoids of below-average height, with large eyes and an emblem that resembled a winged serpent. According to journalist Crisnel Longino, "UFO researchers noted that similar symbols appeared in other reports, including cases from Latin America in 1969, Buenos Aires in 1972, [and] Provo, Utah in 1965". William Herrmann reported a similar encounter involving a winged serpent emblem in 1979, a few months after Filiberto Cardenas reported an incident where, via hypnosis, he recalled witnessing unknown humanoids which, according to author Richard L. Thompson, had "elongated eyes with eyelashes, small flattened noses, long lipless mouths, and light beards". Further, a serpent over a "lazy X" emblem was described. Skeptics have questioned the use of hypnosis with regard to purported encounters in general, as in the case of Schirmer's hypnotic regression. Insectoids Praying Mantis Insectoids Insectalin This classification of alleged extraterrestrial is described as having an insectlike or mantid appearance. They feature in some purported abduction accounts, characterized as taking on a commanding role. As with other beings described in alien abductions, a common prosaic explanation suggested for sightings of insectoid beings is sleep paralysis. Little green men Emilcin abduction L. R. Johannis' encounter in Villa Santina "Little green men" is a common shorthand description for extraterrestrial narratives in general, often used pejoratively by critics of ufology. Even though some purported encounters have referred to alleged beings with green skin, very few reports have ever involved anything that would fit the general description of "little green men". They are included here mainly for cultural reference to the term. As in the case with greys, skeptics suggest that the few such reports in abduction narratives are the result of sleep paralysis. Living UFOs Kenneth Arnold, the man whose 1947 sighting helped coin the phrase "flying saucer" and usher in the modern age of ufology, speculated in 1955 that UFOs themselves may be living organisms, although a man named John Philip Bessor is generally credited as the first to propose this hypothesis six years earlier. Men in black One common theory for the identity of the alleged "men in black" is that of an extraterrestrial origin, due to reported anomalies in appearance and mannerism. Writer Benjamin Radford, though skeptical about the "men in black" phenomenon in general, stated: "It is of course possible that at some point dark-suited men from government agencies made inquiries into UFO reports; there was, after all, an Air Force program that investigated flying saucer claims in the 1950s called Project Blue Book. Government officials (including those with the military, police, Secret Service, FBI, or IRS, for example) are sometimes known to throw their weight around and intimidate people, even unintentionally." He did not, however, seriously consider the notion of MIBs as non-terrestrial entities aside from mentioning the hypothesis. "Michelin Men"