"We are told that in every spot in Roman Alexandria one was bound to come upon a group of noisy and disrupting Cynics, 'bawling out the usual street corner invocations to Virtue in a loud, harsh voice, and abusing everyone without exception,' as Lucian describes them (The Passing of Peregrinus)."
Navia, Luis E. Classical Cynicism: A Critical Study. 1996.
Rather than a school of philosophy, Cynicism refers to an informal group of philosophers with certain attitudes and unconventional behaviors who either called themselves Cynics or were so-called by others.
The goal of Cynicism was to attain arete (Greek) or virtus (Roman), a quality we imperfectly translate "virtue." [See "Virtue and Circumstances: On the City-State Concept of Arete," by Margalit Finkelberg.AJPh, Vol. 123, (Spring, 2002), pp. 35-49.] It is the strength to overcome one's thoughts, feelings, and the circumstances of one's life. Because arete was their goal, Cynics disregarded social conventions and appearance, making them pariahs: What would have shamed their contemporaries did not shame the Cynics. Self-sufficiency required practice (askesis). They required freedom and frankness, which politics disallowed. Classical Cynicism is credited with founding anarchism.
Antisthenes, an associate of Socrates, is counted the 1st Cynic, making Cynicism an offshoot of Socratic teaching. The latest practitioner of classical Cynicism was Sallustius (5th C.). In between were, among others, Diogenes of Sinope, Crates of Thebes, Hipparchia and Metrocles of Maroneia, Monimus of Syracuse, Menippus, Bion of Borysthenes, Cercidas of Megalopolis, Meleager and Oenomaus of Gadara, Demetrius of Rome, Demonax of Cyprus, Dio Chrysostom, and Peregrinus Proteus.
R. Bracht Branham says Antisthenes as the founder of Cynicism was probably an ancient fabrication; Diogenes the Cynic was probably the real one.