Robert Calder

 is a central character featured in the 1957 film 20 Million Miles to Earth. He was played by actor William Hopper.

Biography
Colonel Robert Calder was an astronaut and the leader of the first manned space flight to the planet Venus. Aboard the interplanetary space vessel the XY-21, Colonel Calder and a crew of seventeen astronauts and scientists made the twenty-million mile journey and collected mineral samples to bring back to Earth. One of the samples was a viscous fluid, which contained a Venusian life form in an embryonic state. It was Calder's hope that by studying the life form, scientists might be able to determine a way to make life on Venus possible for people from Earth. Thirteen months later, the XY-21 made its return voyage back to Earth, but its course was diverted after it was struck by a passing meteor. Rather than returning to the United States, the ship crash-landed in the Mediterranean Sea off the coast of Sicily. A passing fisherman and a young boy named Pepe found the XY-21 and helped the survivors make it back to shore. Calder was one of the luckier passengers returning from the voyage as many members of the expedition suffered severe radiation sickness due to exposure from the meteor.

The Venusian life form escaped from the canister he had been kept in and quickly began growing in size and mass. Calder tracked it down halfway to the town of Messina where it was cornered inside of a farmer's barn. He tried poking at the Venusian with a pitchfork, but it escaped from him, heading further into the town.

Colonel Calder coordinated with local Italian authorities as well as the military to stop the creature. He told them that the creature existed on a diet of sulfur and was susceptible to high volts of electricity. They radioed in for helicopters to drop bags of sulfur about the area in order to lure the creature to a predetermined location. Once doing so, they dropped an electrically charged net over top of him. The monster struggled to break free, but ultimately, he was captured. Calder and the others packed him up and prepared to take him to Rome for further study.

The alien continued to grow, reaching a height in excess of thirty-five feet tall. It escaped captivity and began rampaging through the streets of Rome. Colonel Calder arrived and tried stopping the alien's advance by ramming it with his car, but this only succeeded in making the monster even angrier. The Venusian escaped custody by fleeing into the nearby Tiber River.