The Laocoön is a recurring theme among renaissance painters, combining Greek high-drama and violent death. The scene depicts the death of the Laocoön, a Trojan priest of Posidon. During the Greek seige of Troy, it was the Laocoön that mistrusted the now infamous Greek horse. But the god's were on the side of Greece, and the Laocoön's warning earned him and his sons a cursed death by sea-snake. Rough.
El Greco's depiction is a dark one, less classically influenced and trapped by the low clouds he often depicted over his adopted city of Toledo, Spain. The men's contorted bodies are radically stretched in the Mannerist form, their faces tortured. The Laocoön was El Greco's only painting of a mythologial theme, and its violence and vengeful gods may have been a reference to the ravages of the Inquisition, which gripped Spain in the early 1600's.