The Hydra is a large, multi-headed monster sea serpent and the older cousin of Hydros who appears in 1997 Disney animated film Hercules. It was voiced by Frank Welker (from Aladdin). The Hydra tries to kill and eat Hercules.
The Hydra is the first obstacle sent by Hades to kill Hercules. It is trapped under a boulder until Hercules unknowingly releases it in rescuing two boys from under the same boulder who turn out to be none other than Pain and Panic (Hades' henchmen) in disguise. The two thank Hercules before running off to Hades and leaving the hero to feel a false sense of accomplishment, oblivious to what consequences would come of his actions.
The Hydra surprises Hercules by approaching him from the back, forcing the hero into combat until the monster lunges at him and knocks his sword back. Hercules defenestrates the beast by hurling a boulder into its mouth, but it only crushes it into stones and laughs. When the monster next strikes, he holds its mouth open and slams it head into the ground, giving him time to grab his sword. However, the Hydra wraps its tongue around his ankle, hurls him into the air, and swallows him. While in the monster's throat, Hercules decapitates it with his sword from the inside-out. The hero is again lured into a false sense of security before, as Hades expects to happen, the Hydra sprouts three more heads like the lion and the goat and this tail sprout venomous red serpent. It chases down Hercules and causes the spectators in the stands to scatter. Pegasus then lifts the hero off the ground and Hercules fights back, to little avail. With each head he chops off, three more grow.
Hercules is knocked off Pegasus and falls into the the monster's forest of heads, he barely makes it through before he is sent flying through the air. The Hydra then grabs him and as it is about to finishes the young hero off, Hercules notices a rocky cliff that he quickly punches which courses an avalanche of rocks to fall. The Hydra froze as both of its heads look up in fear, when it and Hercules are soon buried and crushed, finally killing the Hydra for good.
All that is seen of the Hydra after the rockslide was its right arm, Phil, Pegasus and Hades then thought that Hercules was now dead, however all the sudden the Hydra's arm started moving, the people are afraid at first thinking that the Hydra is still alive, until it was revealed to be none other then Hercules who survived, everyone soon started cheering for Hercules as the light shine on a new hero. Some time later, the Hydra was revived as a constellation.
During the song "Zero to Hero", everyone is watching a play of how Hercules bravely fought the Hydra in battle.
The Hydra was killed after getting buried under the rockslide by Hercules.