The Darth Vader Death Star Transformer could be the coolest toy ever made!  It combines the best of two worlds; Star Wars and Transformers!  This toy was released sometime around the release of the Transformers movie in '07. The Death Star Transformer is made by Hasbro.  It comes with a Darth Vader mini figure, two tie fighters and three Stormtroopers.
 

STAR WARS TRANSFORMERS DARTH VADER DEATH STAR MINT    US $60.00

Star Wars Death Star Darth Vader Transformer    US $7.50

Star Wars Transformers Darth Vader Death Star RARE    US $30.05

I wish every Transformer figure was this cool.