Benevolent Alien Invasion: Well, sort of.  It’s almost never an invasion (although there are some groups, like, say, the Sanguinary Enforcers of the Liberty Ethic, who don’t mind holding Blast The Shit Out Of The Oppressors And Bugger Off Again Day from time to time).  Much more common is the First Contact Whose Aftereffects Are Pretty Benevolent, But Really, All They Had In Mind Was Entering A New Emerging Market.