This is the Scorpian - a humanoid scorpion.

The original idea was that the Scorpi had left humanity to search for other strange creatures like themselves. Later, a small group of adventurers discovered and ancient temple that was apparently built by an ancient race of scorpion people. They continued their research until it was apparent that the Scorpi were actually still alive. Later, one of the adventurers discovered an ancient passageway beneath the city...