Louie wasn't terribly impressive in his early days. He seemed to have one moving iteration, with some very human legs, but was usually just something you had to wheel around to games.
He also got no respect.
Cue Cathi Brockman, who had worked at Astroworld in these suffocating costumes and was just crazy enough to suggest bringing Louie to life. S/he debuted in Fall 1987.
(I always think Louie when I see this episode of King of the Hill.)
10/1/87 Leader Front Page: Louie
The Longhorns' new mascot debuted at Saturday's football game against Rayburn. Inside the costume is junior Cathy Brockman who came up with the idea for a mascot. Companies donating or more to the cost of the uniform will have their names branded on Louie Longhorn.
Over the years, it appears Louie has been joined by Lucy, but I cannot find any photos of them online through a Google Search. I will have to see if I can get some scanned on a future trip.