Dao was a human who held the rank of admiral within the naval branch of the Galactic Republic during the Clone Wars.
In 22 BBY, Dao participated in a planetary engagement of the world of Ryloth, where he commanded a relief supply fleet of Republic Star Destroyers. During the battle, the Republic officer and his fleet attempted to repel a Separatist Alliance blockade of warships led by Neimoidian Captain Mar Tuuk in Ryloth's orbit.
During the battle, the Republic officer's forces had been rendered critically low on resources and were in no position to provide aid to the forces of Jedi General Ima-Gun Di on the surface. Soon thereafter, Dao was killed amid a conversation with the Jedi High Council, when an explosion claimed his Star Destroyer. As a result of Dao's death, the Separatist blockade was able to establish a planetary defense in orbit, while Di's forces continued to battle the Separatist Droid Army below.
Dao wore the standard military uniforms of the Republic's military branch. The uniform was also accompanied by a insignia plaque showing three red and two blue squares in order to indicate Dao's rank of admiral.
Dao was introduced in "Supply Lines," the third episode of the third season of the Star Wars: The Clone Wars television series, which aired on September 24, 2010. The character was voiced by James Arnold Taylor, who also voiced Obi-Wan Kenobi in the same series.