Spawn of Crota
From Destiny 1 Wiki
The Spawn of Crota are a sect of the Hive. This is the sect devoted directly to the god Crota, and seek to complete his will by conquering Earth. In the base game they are sometimes encountered within the Hellmouth, but play a much bigger role in The Dark Below, as they increase their activities on Earth, including the attempted revival of their master Crota. They are identified by their yellow coloring.