Octaman

Octaman is a 1971 monster film directed by Harry Essex. It follows an expedition team that becomes the target of a murderous humanoid octopus. The film has gathered a cult following. Future Academy Award Winner Rick Baker created the monsters suit in what appears to be his first uncredited motion picture work.

The scientists return to the camp in an RV a few days later and find it abandoned. Davido, a young Indian man from the nearby village, says that a local legend about a creature said to be half man and half sea serpent is true, and offers to take the scientists to the lake where it is purported to live. Meanwhile, Octaman kills some villagers. The next day, the scientists find another small mutant octopus, and Octaman has gone to the camp and killed a crew member and escaped. Johnny, witness to the attack, decides to capture the monster for his circus.Octaman returns to the RV, but Lowry honks the horn to signal for help. The other scientists arrive and the monster flees. They go searching for it on the lake, and it pulls down another crew member out of their boat. When it reappears at the RV and captures Lowry, they blind it with their flashlights to stop it in its tracks, then light a ring of gasoline around it. The fire consumes enough oxygen that the monster suffocates and falls unconscious, and Lowry gets rescued. They finish the capture by tranquilizing it and trapping it under a net. In the morning, however, a thunderstorm brings rain which revives the Octaman and allows it to escape. It moves to seize Lowry, but she manages to communicate with it and send it away. ........

Source: Wikipedia