This Island Earth (1955)

In the cerebral 1950's science-fiction film by director Joseph M. Newman:

• the scene in which big foreheaded, white-haired alien Metalunans ensnared Dr. Cal Meacham (Rex Reason) and Dr. Ruth Adams (Faith Domergue) in their tractor beam and took them to the surrealistic doomed planet of Metaluna
• their encounter with slave "Mut-Ants" (giant insects with an enlarged, exposed brain)
• the scene in which Cal, Ruth and benevolent Metaluna emissary Exeter (Jeff Morrow) escaped the destruction of Metaluna
• the attack by a stowaway Mut-Ant
• Exeter's sacrificial suicide (by crashing his saucer into the ocean) after telling Cal and Ruth to leave in their biplane