Who is trimachio in The Great Gatsby?

Trimalchio is an early version of The Great Gatsby

I don't think that there's a character called Trimalchio in Trimalchio, or in The Great Gatsby.

It seems to be some sort of symbol, connected to a character of that name in something called Satyricon by Petronius (AD 27-66). In that text, Trimalchio is a freed slave who has grown wealthy and hosts a lavish banquet; that's an obvious link with Gatsby so I suspect that was the reason for that earlier title.