Thunderbird Bay is a census-designated place (CDP) in Brown County in central Texas, United States. As of the 2020 census, Thunderbird Bay had a population of 764.
Thunderbird Bay is located in north-central Brown County along the northern arm of Lake Brownwood, a reservoir on Pecan Bayou. By road, the CDP is north of Brownwood, the county seat.
According to the United States Census Bureau, the CDP has a total area of , of which is land and , or 13.42%, is water.
Thunderbird Bay first appeared as a census designated place in the 2010 U.S. census.
As of the 2020 United States census, there were 764 people, 357 households, and 141 families residing in the CDP.