The Lernaean monster or also know as the Hydra had nine heads, and one of these was immortal. If ever a mortal head was cut, from the stump would immediately spring forth two new heads. The hydra lived in the swamps and ravaged the countryside devouring cattle, until Hercules, with the help of Iolaus, put an end to it by burning the the neck stumps after severing the heads. When Hercules cut off the immortal head, he buried it underground with a stone to hold it down.
The Hydra is a nine headed Greek monster that grows two new heads every time one is chopped off. The only way it can be killed is if the necks are singed before the two new heads grow back. That is how Hercules killed it.
Python was the name of a monster killed by Apollo. Other monsters were killed by Zeus and Hercules.
The Lernaean Hydra.
Probably Hercules but the story has been retold many times so there are probably different titles.
Hercules killed the hydra, not odysseus
Guarding the entrance to the underworld, that hellhound's name is Cerberus.
Scylla.
Minotaur.
The Nemean lion.
Pain and Panic never actually turned into a monster. At the beginning, when they kidnapped baby Hercules, they turned into snakes. Later, when Hades found out they hadn't killed Hercules as a baby, they turned into worms. When they were trying to lure Hercules into the Hydra trap, they turned into little boys. When they were spying on Meg to make sure she found out Hercules' weakness, they turned into song birds. And then near the end, they lured Pegasus into a back room by turning into a female pegasus.
Five-Headed Dragon.
The creature that Herakles (the real name of Hercules, which means "son of Hera", who was Greek, but called Hercules by the Romans) slayed was not a woman. It was a serpent called the Hydra, meaning "water creature".