A Cort Jazz Bass copy that I got in the early 80s and looked exactly like a Geddy Lee bass with the bound and blocked fretboard and the whole bit. I'll bet it weighed 12 pounds.
I had one of those, in sunburst, it was my second bass, purchased from a co-worker for $100. Mine wasn't 12 lbs, but it was heavier than some that I've owned. I rarely played it, the pickups were awful, and even after a setup attempt by a local tech it just never played very well.