Waco was a 19th century Human man, a criminal who lived in southern California.
History[]
In the 1850s, Waco was a member of Billy Clancey’s outlaw gang in the Old West. After being broken, his left hand had not been properly reset.
In the year 1855, the gang robbed a stagecoach carrying a time traveling Montgomery Scott. Scott overheard Waco's hopes of seeing a visiting doctor who performed miracle cures, hoping to get his hand fixed, and thought this might be the doctor he was pursuing through time. When Waco tried to rob Scott, the officer quickly shot the cowboy's hat out of his hand with a phaser. Thinking on his feet, Scott claimed the weapon was a "trick gun" he invented, then asked for work. Clancey hired him, allowing Scott to stick close to Waco.
Later, Waco tossed glass bottles in the air for Scott as target practice. Waco told Clancey they should rob a wagon train hauling Mexican silver. Clancey agreed, knowing Scott's weapon could overpower any guards, and stole the phaser while Scott slept.
Scott pursued the thieves on horseback and helped stop the robbery. Afterwards, Waco led Scott into town to see the miracle doctor. Unfortunately, he turned out to be just a snake oil salesman named Smith. (TOS comic: "A Bomb in Time")