That massive (but still small) Kenner die cast metal Star Destroyer.
My favorite ship design of the movies was the Star Destroyer and as a kid the only version I saw was the seven inch or so chunk of metal. Lost the little plastic Tantive IV it came with immediately, but I was totally okay with that.
As time has gone on I've lost that original ship as well. Now I just have my bigger plastic Collector Fleet version. Not so nostalgic for it however.