Any old giant robots that are not Japanese??
Well, here’s a few off the top of my head:
One of my favorites has to be “the Iron God” by Jack Williamson, from 1941. It’s exactly like Williamson’s other story about evil robots, “the Humanoids,” where superintelligent and superpowerful robots that can out-think humans emerge and micromanage us for our own protection. The ending of “the Iron God” is a bit of a downer. I have no idea where people got it in their heads that pulp era science fiction was all about optimistic futures.
You also have the Metal Emperor from A. Merritt’s horror/lost world story, “The Metal Monster,” about a lost city of living metal men discovered in the Himalayas.
All-American Boy inventor Tom Swift built a giant robot in his own series.
Magnus, Robot Fighter fought a giant probe robot in his comic of the same name.
Okay, I’m going to ask you something, and I would like you to think about it before giving an the immediate response: do the Martian tri-legged fighting machines from War of the Worlds count as mecha? I think they do. They’re legged machine craft with a pilot inside. This is potentially a “is a hot dog a sandwich” question, but I think the tripods count as mecha by the modern definition.