Darth Vader

noun2

1. •
   A powerful individual or force, particularly one that is seen as malevolent, dominating and threatening.

   • Irabu had hired Nomura, a man with whom he obviously had a great deal in common, and, who, as we have seen, was rapidly becoming the Darth Vader of Japanese baseball. — 2004
2. •
   (UK, informal) A British Rail Class 460 train.

   • When the new GEX stock (Darth Vaders!!) are in service, and the inevitable happens and they break down, EWS will no doubt trundle along to rescue it — 1999