Possible Clues:

• Presumed 8-Down pilot
• Pork pie eaten by an outsider
• 1979 sci-fi classic with three sequels and two prequels
• Sci-fi figure
• Visitor from the stars
• That's a right sort of a foreigner
• 1979 sci-fi thriller
• "Star Trek" extra
• Earth invader
• Venusian, e.g.