This honor goes to the October 1977 issue of Dirt Bike magazine, which had an authoritative Darth Vader looming large over his trusty dirt bike, "Droid." The fact that such a pairing never made it to The Empire Strikes Back just reeks of wasted potential.

This image comes to us courtesy of the Star Wars magazine cover archive. Other strong contenders for the above headline's superlative are the November 1977 issue of 1001 Van and Truck Ideas, Custom Vans circa April '78, the March 1980 issue of 321 Contact (which seemed to imply Empire was a covert documentary) and the not safe for work February 1978 cover of Film and Filming magazine, which juxtaposed Luke Skywalker next to some casual nudity.

[Spotted on What The Fett]