A Jewel bug, Metallic Shield bug, or a Shield-backed bug. If only common names for insects were more standardized like they are for birds. Not sure how feasible that would be though. This is a bug belonging to the family Scutelleridae.
Bugs belonging to this family are often much more fancy looking than this one, in case you were wondering why it’s called a Jewel bug. They feed on the sap from plants. Being closely related to stink bugs, most are also capable of releasing a foul odor as a defense mechanism.