Hasslo was a Mirialan male Jedi Master who served the Jedi Order and the Galactic Republic as a Jedi combat instructor, during the Galactic War with the Sith Empire. Olive-skinned, Hasslo had blue eyes and diamond-shaped tattoos on his chin, wearing white armor over brown robes. While he was bald, Hasslo had black eyebrows, and he wielded a single lightsaber. The Jedi Master was stationed at the Minimum Security Section of the Republic prison complex on the planet Belsavis.