Sharquoi

In the Conversations from the Universe booklet found in Halo 2: Limited Collecter's Edition, an Elite refers to something called the Sharquoi. This has been assumed to be another Covenant race. In a deleted scene, a mural can be seen showcasing the Covenant races, including a very large creature assumed to be a Sharquoi. Because of its similarity with the Drinol, many speculate they are the same.

From a Bungie Weekly What's Update:

Q: What's a Sharquoi? A: Very freaking dangerous.

Frankie has talked about playing Halo 3, and fighting Grunts and "something larger than a Grunt," supporting the idea that the Sharquoi will be seen in Halo 3.