Homo homini lupus
Homo homini lupus is a Latin phrase meaning "man is a wolf to [his fellow] man." It has meaning in reference to situations where people, usually and predominantly males, are known to have behaved in a way comparably in nature to a wolf. The wolf as a creature is thought, in this example, to have qualities of being predatory, cruel, inhuman i.e. more like an animal than civilized.
Reflections by later thinkers
Thomas Hobbes recognised the existence of a state of nature into which is set men who behave as if wolves, in the Leviathon,  and he drew upon the aphorism in the dedication of De Cive (1651): "To speak impartially, both sayings are very true; That Man to Man is a kind of God; and that Man to Man is an errant Wolfe. The first is true, if we compare Citizens amongst themselves; and the second, if we compare Cities."
Hobbes described the tendency of people to behave mercilessy amongst themselves if not influenced by the powers of government to not do so. 
The person Sigmund Freud made some analysis of the axiom, locating the wolfishness of humanity, male humans especially, within the influence in society of instinctual drives and motivations, these things beings kept necessarily in check always within, and for, a civilized world. 
- Erasmus discusses Plautus' use of the phrase in Adagia (1500).
- Used ironically in Voltaire's Candide (1759) to argue against the philosophy of optimism
- Founding assumption of Sigmund Freud's Civilization and Its Discontents (1929)
- Cited on p. 211 of the third volume of Klaas Schilder's Christus in Zijn lijden trilogy
- Quoted in Marianne Moore's World War II poem "In Distrust of Merits".
- In chapter 13 of Doctor Zhivago (1957) by Boris Pasternak, the narrator remarks, of the scenes and events witnessed by Zhivago as he evades partisans late in Russia's post-revolutionary civil war: "Those days justified the ancient saying that 'man is a wolf to man'."
- Quoted in Eine Frau in Berlin (1959), an anonymously published autobiography posthumously attributed to Marta Hillers
- In Patrick O'Brian's The Wine-Dark Sea (1993), parson Nathaniel Martin uses the phrase to comment on his shipmates who have become cheerfully avaricious in anticipation of more treasure from enemy ships.
- Man Is Wolf to Man (1999), a memoir by Janusz Bardach
- Motto of a family of werewolves in Terry Pratchett's The Fifth Elephant (1999) Criticised by one of the werewolves in the novel: 'And our family motto is Homo Homini Lupus. "A man is a wolf to other men"! How stupid. Do you think they mean that men are shy and retiring and loyal and kill only to eat? Of course not! They mean that men act like men towards other men, and the worse they are the more they think they'd really like being wolves!' (p.333)
- In part 6, chapter I of Wolf Hall (2009) by Hilary Mantel, Thomas Cromwell recalls the phrase whilst reflecting on the Duke of Norfolk's hounding of Cardinal Wolsey.
Cinema and television
- In Marco Bellocchio's directorial debut Fists in the Pocket (1965), a man chats with a girl in a nightclub and tries to explain this phrase to her.
- Title of Episode 14 of Season 1 of Law & Order: Criminal Intent
- Title of an Italian short movie directed by Matteo Rovere in 2006
- Seen on a wall of the Main Cell Block of the Penitentary in the video game Batman: Arkham Asylum (2009)
- The character Hot Coldman has the phrase tattooed on the back of his head in the game Metal Gear Solid: Peace Walker (2010)
- The title of an achievement in the Faction Pack DLC for Metro: Last Light (2013)
- The title of an achievement/trophy in the 2015 survival horror video game Dying Light.
- T.K. Christov. Leviathans Tamed: Political Theory and International Relations in Modern Political Thought (foot of p.42). ProQuest, 2008 ISBN 054998013X (281 pages). Retrieved 2015-05-16.
- C Schmitt. The Nomos of the Earth in the International Law of the Jus Publicum Europaeum (translated by G. L. Ulmen) - p.95-96. Telos Press Publishing, 1 Jan 2003 (reprint) ISBN 0914386301 (372 pages). Retrieved 2015-05-16.
- "Homo, sacra res homini (...)". Lucius Annaeus Seneca: Epistulae morales ad Lucilium, XCV, 33.
- review by J. Gray of. The Philosopher and the Wolf: Lessons from the Wild on Love, Death and Happiness by M Rowlands. Literary Review. Retrieved 2015-05-17.
- D.C. Abel - Freud on Instinct and Morality SUNY Press, 1 Jan 1989 ISBN 0791400247 (123 pages) [Retrieved 2015-05-16](p.79 - "...Society believes that no greater threat to its civilization could arise than if the sexual instincts were to be liberated and returned to there original aims..." Freud 1916-17)
- English translation by Manya Harari and Max Hayward, William Collins & Co, 1958.