Pergamus was an ancient Greek warrior, the son of Pyrrhus and Andromache. He is most known for waltzing into the kingdom of Teuthrania (located in modern day Turkey near the Aegean coast), challenging its king to a feat of strength, killing said king, and renaming the place (and its capital) after himself. Today the city still stands and is known as Bergama.
Long after his death, the term "Pergamus" became synonymous with "mountain" (and may be the source for the German word berg) and the city of Troy's citadel was named Pergamus in a fashion. The Book of Revelations mentions both Troy and Pergamus with respect to the coming Apocalypse.
The great physician Galen hailed from the city of Pergamus. In the year 399, Xenophon captured Pergamus for the Greeks, but it was recaptured by the Persians shortly thereafter. When the citizens of the town revolted, they were punished harshly by their Persian overlords, and thus it is often that you see allusions to Pergamus with regards to being punished for speaking one's mind.
Boring Etymology Alert: Pergamus is Latin for "let us proceed".