During the course of his life, Heracles married four times.

His first marriage was to Megara, whose children he murdered in a fit of madness.

According to Pseudo-Apollodorus Megara was unharmed. According to Hyginus, Heracles also killed Megara.

His second wife was Omphale, the Lydian queen to whom he was delivered as a slave.

His third marriage was to Deianira, for whom he had to fight the river god Achelous. Soon after they wed, Heracles and Deianira had to cross a river, and a centaur named Nessus offered to help Deianira across but then attempted to rape her. Enraged, Heracles shot the centaur from the opposite shore with a poisoned arrow and killed him.

His fourth marriage was to Hebe, his last wife.

More Info: en.wikipedia.org