"One of these days you're going to learn to watch your back."
- – Walker, to Michael Garibaldi
Walker Smith was a human professional boxer, and close friend to Michael Garibaldi.
At one point, Smith was in a Fortune City Holopeep. He started a fight while he was there and, Garibaldi, working security there, arrested him with his shock stick. This was where the two met and they would become friends afterward.
In 2256, Smith was a rising star in professional championship boxing. He traveled from Orion IV to Mars, Io and the LaGrange Stations, and earned enough to buy passage to Earth as well a boxing license that would allow him to fight Atagi in a match some would call "World War 4." After his victory, Smith became the number one contender for the title, however, SportCorp, having invested a significant amount of money in Vizaro, the title holder, approached Smith with the suggestion that he should retire for a few years. He refused, and so SportCorp tampered with his blood test to make it look like he'd been using adrenals and accused him of working for the Syndicate. The news networks jumped on the story, and, as a result, Smith lost his licence and was unable to get a legitimate fight for the next two years.
In 2258, Smith arrived at Babylon 5 to participate in an all-alien Mutai fight circuit. He hoped that the publicity would help him reignite his boxing career. Initially denied from participating, Smith received the aid of a former Mutari, Caliban, and eventually entered the competition. With Smith's entrance into the competition, he paved the way for other humans to join. 
- Lawrence G. DiTillio named the character after the boxer Sugar Ray Robinson, whose real name was Walker Smith.