Personally, I've never been able to figure out why the producers of Trek over the past twenty or so years haven't used the Gorn race as a "big bad."
With the exception of a mirror universe cameo on 'Enterprise,' the only time they were ever shown was on a single episode of TOS so you don't have the overuse factor of Romulans, Klingons, Ferengi, etc. What you do have, however, is a race of near invunerable, seven foot tall, predatory, talking lizard people. Those guys could, if written well, eat the Klingons for lunch.
If you believe the stories, Harlan Ellison pitched a story that could've used them quite nicely back when they were making the first Trek flick.