The original Silenus resembled a folklore man of the forest with the ears of a horse and sometimes also the tail and legs of a horse. The later Sileni were drunken followers of Dionysus, usually bald and fat with thick lips and squat noses, and having the legs of a human. Later still, the plural "Sileni" went out of use and the only references were to one individual named Silenus, the teacher and faithful companion of the wine-god Dionysus. A notorious consumer of wine, he was usually drunk and had to be supported by satyrs or carried by a donkey. Silenus was described as the oldest, wisest and most drunken of the followers of Dionysus, and was said in Orphic hymns to be the young god's tutor. This puts him in a company of phallic or half-animal tutors of the gods, a group that includes Priapus, Cedalion and Chiron, but also includes Pallas, the tutor of Athena.
When intoxicated, Silenus was said to possess special knowledge and the power of prophecy. The Phrygian King Midas was eager to learn from Silenus and caught the old man by lacing a fountain from which Silenus often drank. As Silenus fell asleep, the king's servants seized and took him to their master.
Silenus shared with the king a pessimistic philosophy: That the best thing for a man is not to be born, and if born, should die as soon as possible.
An alternative story was when lost and wandering in Phrygia, he was rescued by peasants and taken to King Midas, who treated him kindly. Dionysus offered Midas a reward for his kindness towards Silenus, and Midas chose the power of turning everything he touched into gold. Another story was that Silenus has been captured by two shepherds, and regaled them with wondrous tales.
In Euripides's satyr play Cyclops, Silenus is stranded with the Satyrs in Sicily, where they have been enslaved by the Cyclops. They are the comic elements of the story, which is basically a play on Homer's Odyssey IX. Silenus refers to the satyrs as his children during the play. Silenus also appears in Emperor Julian the Apostate's satire, The Caesars, where he sits next to the gods and offers up his comments on the various rulers under examination. He essentially serves as Julian's voice of critique for Alexander the Great, Julius Caesar, Augustus, Marcus Aurelius (whom he reveres as a fellow philosopher-king), and Constantine I.
Silenus was also possibly a Latin term of abuse around 211 BC, being used in Plautus' Rudens to describe Labrax, a treacherous pimp or leno, as "...a pot-bellied old Silenus, bald head, beefy, bushy eyebrows, scowling, twister, god-forsaken criminal"
During late 19th century Germany and Vienna, symbolism from ancient Greece was reinterpreted through a new Freudian prism. Around the same time Vienna Secession artist Gustav Klimt uses the irreverent, chubby-faced Silenus as a motif in several works to represent "buried instinctual forces".
Silenus commonly figures in Roman bas-reliefs of the train of Dionysus, a subject for sarcophagi, embodying the transcendent promises of Dionysian cult. The figure reappears with the Renaissance: a court dwarf posed for the Silenus-like figure astride a tortoise at the entrance to the Boboli Gardens, Florence. The Drunken Silenus, Peter Paul Rubens, painted in 1616-17 is conserved in the Alte Pinakothek, Munich.
Silenus appears also in Schopenhauer's works (particularly his most famous dictum), and via Schopenhauer, in Nietzche.
Silenus appears as an amorous satyr in the children's story, Odysseus in the Serpent Maze, by Jane Yolen and Robert J. Harris.
Silenus is an old fat satyr in Rick Riordan's Percy Jackson and the Olympians series.