Sources of Aesop's life date from long after his death, and most biographical material about him is almost certainly mythical. His name was associated with a huge number of fables, most of which probably were composed not by the historical figure of Aesop but by later authors.

The earliest Greek sources (including Aristotle) indicate that Aesop was born in Thrace at a site on the Black Sea coast which would later become the city Mesambria; a number of later writers from the Roman imperial period (including Phaedrus, who adapted the fables into Latin), say that he was born in Phrygia. The 3rd-century B.C. poet Callimachus called him "Aesop of Sardis," and the later writer Maximus of Tyre called him "the sage of Lydia".

Aristotle is also the earliest source (following Herodotus) for the information that Aesop was a slave in Samos and that his masters were first a man named Xanthus and then a man named Iadmon; that he must eventually have been freed, because he argued as an advocate for a wealthy Samian; and that he met his end in the city of Delphi. Plutarch tells us that Aesop had come to Delphi on a diplomatic mission from King Croesus of Lydia, that he insulted the Delphians, was sentenced to death on a trumped-up charge of temple theft, and was thrown from a cliff; the Delphians subsequently suffered pestilence and famine. Before this fatal episode, Aesop also met with Periander of Corinth, where Plutarch has him dining with the Seven Sages of Greece, sitting beside his friend Solon, whom he had met in Sardis.

Problems of chronological reconciliation dating the death of Aesop and the reign of Croesus led the great Aesop scholar Ben Edwin Perry in 1965 to conclude that "everything in the ancient testimony about Aesop that pertains to his associations with either Croesus or with any of the so-called Seven Wise Men of Greece must be reckoned as literary fiction," and Perry likewise dismissed Aesop's death in Delphi as legendary; but subsequent research has established that a possible diplomatic mission for Croesus and a visit to Periander "are consistent with the year of Aesop's death." Still problematic is the story by Phaedrus which has Aesop in Athens, telling the fable of the frogs who asked for a king, during the reign of Peisistratos, which occurred decades after the presumed date of Aesop's death.

Along with the scattered references in the ancient sources regarding the life and death of Aesop, there is a highly fictional biography now commonly called The Aesop Romance (also known as the Vita or The Life of Aesop or The Book of Xanthus the Philosopher and Aesop His Slave), "an anonymous work of Greek popular literature composed around the second century of our era....Like The Alexander Romance, The Aesop Romance became a folkbook, a work that belonged to no one, and the occasional writer felt free to modify as it might suit him." Multiple, sometimes contradictory, versions of this work exist. The earliest known version "was probably composed in the first century C.E.," but the story "probably circulated in different versions for centuries before it was committed to writing"; "certain elements can be shown to originate in the 4th century B.C.E." Scholars long dismissed any historical or biographical validity in The Aesop Romance; widespread study of the work began only toward the end of the 20th century. A full assessment of its value has yet to be presented.

In The Aesop Romance, Aesop is a slave of Phrygian origin on the island of Samos, and extremely ugly. At first he lacks the power of speech, but after showing kindness to a priestess of Isis, is granted by the goddess not only speech but a gift for clever storytelling, which he uses alternately to assist and confound his master, Xanthus, embarrassing the philosopher in front of his students and even sleeping with his wife. After interpreting a portent for the people of Samos, Aesop is given his freedom and acts as an emissary between the Samians and King Croesus. Later he travels to the courts of (the imaginary) Lycurgus of Babylon and Nectanabo of Egypt in a section that appears to borrow heavily from the romance of Ahiqar. The story ends with Aesop's journey to Delphi and his death there.

Though Aesop became famous across the ancient world as the preeminent teller of fables, he did not create the genre; the earliest known story with talking animals in ancient Greek is the fable of the hawk and the nightingale from Hesiod, who lived at least three centuries before Aesop.

Aesop may or may not have written his fables...The Aesop Romance claims that he wrote them down and deposited them in the library of Croesus; Herodotus calls Aesop a "writer of fables" and Aristophanes speaks of "reading" Aesop...but no writings by Aesop have survived.

Socrates while in prison turned some of the fables into verse. In Plato's dialogue Phaedo, which takes place on the day of Socrates' execution, Socrates speaks of a recurring dream which exhorted him to "make music" and which he took to refer to philosophy, but after his trial he decided to try to write poetry: "As I have no invention, I took some fables of Aesop, which I had ready at hand and knew, and turned them into verse." Diogenes Laertius in his Lives and Opinions of Eminent Philosophers records a small fragment. The early Roman playwright and poet Ennius also rendered at least one of Aesop's fables in Latin verse, of which the last two lines still exist.

The body of work identified as Aesop's Fables was transmitted by a series of later authors writing in both Greek and Latin. Demetrius of Phalerum (ca. 350-ca. 280 BC) made a collection in ten books, probably in prose (Lopson Aisopeion sunagogai) for the use of orators, which has been lost. Next appeared an edition in elegiac verse, cited by the Suda, but the author's name is unknown. Phaedrus, a freedman of Augustus, rendered the fables into Latin. Babrius turned the fables into Greek choliambics in the earlier part of the 3rd century A.D. Another 3rd century author, Titianus, rendered the fables in prose, now lost. Avianus (of uncertain date, perhaps the 4th century) translated 42 of the fables into Latin elegiacs. The 4th century grammarian Dositheus Magister also made a collection of Aesop's Fables, now lost.

Aesop's Fables continued to be revised and translated through the ensuing centuries, with the addition of material from other cultures, so that the fables known today in some cases bear little relation to the original fables of Aesop. With a surge in scholarly interest in Aesop and Aesopic fable beginning toward the end of the 20th century, some attempt has been made to determine the nature and content of the very earliest fables which may be most closely linked to the historic Aesop.

Perhaps the earliest ancient author to refer to Aesop's appearance is Himerius, who says that Aesop "was laughed at and made fun of not because of some of his tales, but on account of his looks and the sound of his voice." The Aesop Romance begins with a vivid description of Aesop's appearance, saying he was "of loathsome aspect...potbellied, misshapen of head, snub-nosed, swarthy, dwarfish, bandy-legged, short-armed, squint-eyed, liver-lipped...a portentous monstrosity." The evidence from both of these sources is dubious, since Himerius lived some 800 years after Aesop and his image of Aesop may have come from The Aesop Romance, which is essentially fiction; but whether based on fact or not, at some point the idea of an ugly, even deformed Aesop took hold in popular imagination. Scholars have begun to examine why and how this "physiognomic tradition" developed.

Another, more recent tradition depicts Aesop as a black African from Ethiopia. This idea appears to have originated with Planudes, a Byzantine scholar of the 13th century A.D. who wrote a biography of Aesop based on The Aesop Romance and conjectured that Aesop might have been Ethiopian, given his name. (Ethiopian in Greek means "scorched-face," a "vestige of an archaic view of the world that located the Ethiopians to the east, near the rising sun, which was responsible for their blackened skins.") An English translation of Planudes' biography from 1687 says that "his Complexion [was] black, from which dark Tincture he contracted his Name (Aesopus being the same with Aethiops)," and when asked his origin by a prospective new master, Aesop replies, "I am a Negro"; numerous illustrations by Francis Barlow accompany this text and depict Aesop accordingly. But according to Gert-Jan van Dijk, "Planudes' derivation of 'Aesop' from 'Aethiopian' is...etymologically incorrect."

The idea that Aesop was Ethiopian may have been further encouraged by the presence of camels, elephants, and apes in the fables, but these African elements are more likely to have come from Egypt and Libya than from Ethiopia, and the fables featuring African animals may have entered the body of Aesopic fables long after Aesop actually lived.

Ancient sources mention two famous statues of Aesop, one by Aristodemus and another by Lysippus which was in a place of honor before the Seven Sages of Greece, and Philostratus describes a painting of Aesop surrounded by the animals of his fables; none of these works is known to have survived, and we do not know how Aesop was depicted.

In 1843, the archaeologist Otto Jahn suggested that Aesop was the person depicted on a Greek red-figure cup, ca. 450 B.C., in the Vatican Museums. Paul Zanker describes the figure as a man with "emaciated body and oversized head...furrowed brow and open mouth," who "listens carefully to the teachings of the fox sitting before him. He has pulled his mantle tightly around his meagre body, as if he were shivering...he is ugly, with long hair, bald head, and unkempt, scraggly beard, and is clearly uncaring of his appearance."

The 4th century B.C. Athenian playwright Alexis put Aesop on the stage in his comedy "Aesop," of which a few lines survive (Athenaeus 10.432); conversing with Solon, Aesop praises the Athenian practice of adding water to wine.

The 3rd century B.C. poet Poseidippus of Pella wrote a narrative poem entitled "Aesopia" (now lost), in which Aesop's fellow slave Rhodopis (under her original name Doricha) was frequently mentioned, according to Athenaeus 13.596. Pliny would later identify Rhodopis as Aesop's lover (see below).

Some archaeologists have suggested that a Hellenistic statue of a bearded man with a deformed torso in the Villa Albani in Rome depicts Aesop (see photo elsewhere on this page); but as François Lissarrague points out, "It could be the realistic portrait of some individual unknown to us, or an expressive portrait like others known to exist in Hellenistic art. The sole argument advanced to identify the fabulist in this work is the facial expression: He looks intelligent. Admittedly, this evidence is a bit meager."

Aesop makes a cameo appearance in the novel A True Story by the 2nd-century A.D. satirist Lucian; when the narrator arrives at the Island of the Blessed, he finds that "Aesop the Phrygian was there, too; he acts as their jester."

Diego Velásquez painted a portrait of Aesop (dated 1639-40) which is now in the collection of the Museo del Prado. The presentation is anachronistic and Aesop, while arguably not handsome, displays no physical deformities.

The 1687 edition of Aesop's Fables with His Life: in English, French and Latin included 28 engravings by Francis Barlow to illustrate the English translation of Planudes' Life of Aesop; Aesop is shown as a dwarfish hunchback, and his facial features appear to accord with his statement in the text (p. 7), "I am a Negro."

Sir John Vanbrugh's comedy "Aesop" premiered at the Theatre Royal in Drury Lane, London, in 1697 and was frequently performed there for the next twenty years. A translation and adaptation of "Les fables d'Esope" and "Esope à la cour" by French playwright Edmé Boursault, Vanbrugh's play depicted a physically ugly Aesop acting as adviser to Learchus, governor of Cyzicus under King Croesus, and using his fables to solve romantic problems and quiet political unrest.

The success of Vanbrugh's comedy led, beginning in 1697, to a new form of "journalistic-poetical entertainment which consisted of small pamphlets chronicling Aesop's visits to various English spas" where he recounted his fables, often with a contemporary satirical or political bent; these pamphlets had titles like Aesop at Bathe, Aesop at Tunbridge, and Aesop at Islington.

In 1780, the anonymously authored novelette The History and Amours of Rhodope was published in London. Drawing on a mention in Herodotus 2.134-5 that Aesop had once been owned by the same master as Rhodopis, and the statement in Pliny 36.17 that she was Aesop's concubine as well, the story casts the two slaves as unlikely lovers, one ugly and the other beautiful; ultimately Rhodope is parted from Aesop and marries the Pharaoh of Egypt. Some editions of the volume were illustrated with an engraving by Francesco Bartolozzi of a work by painter Angelica Kauffmann depicting Aesop and Rhodope.

In 1844, Walter Savage Landor, famed for his series of Imaginary Conversations, published a fictional dialogue between Aesop and Rhodope in the volume The Book of Beauty; Aesop describes himself as "undersized and distorted."

Turhan Bey played Aesop in the movie Night in Paradise (1946); Aesop is depicted as an advisor to King Croesus who falls in love with the king's intended bride, a Persian princess played by Merle Oberon.

In 1949, Richard Durham's "Destination Freedom" radio show broadcast the drama "The Death of Aesop," in which Aesop was portrayed as an Ethiopian.

"A raposa e as uvas" ("The Fox and the Grapes"), a play in three acts about the life of Aesop by Brazilian dramatist Guilherme Figueiredo, was published in 1953 and has been performed in many countries, including a videotaped production in China in 2000 under the title Hu li yu pu tao or ?????.

In 1953, the teleplay "Aesop and Rhodope" by Helene Hanff was broadcast on Hallmark Hall of Fame. Aesop was played by Lamont Johnson.

Beginning in 1959, animated shorts under the title "Aesop and Son" appeared as a recurring segment in the TV series Rocky and His Friends and its successor, The Bullwinkle Show. Aesop (voiced by Charles Ruggles) would recount a fable for the edification of his son, Aesop Jr., who would then deliver the moral in the form of an atrocious pun.

In 1971, Bill Cosby played the voice of Aesop in an animated TV production, Aesop's Fables.

In 1998, Robert Keeshan played the voice of Aesop in the episode "Hercules and the Kids" in the animated TV series Hercules.

In 2010, the musical play "Aesop's Fables" was produced at the Fugard Theatre in Cape Town, South Africa; Aesop was played by Mhlekahi Mosiea. According to director Mark Dornford-May, "the play tells the story of Aesop, a Greek slave who yearns for freedom and through his journeys he learns that freedom is earned and kept through being responsible. On his journeys he meets animal characters from the seven parable-like fables."