Well, here's the explanation of UNLV's Rebels:
They were rebelling against UNR and the Wolfpack, that was what they were rebelling against
They almost were changed the Minutemen. Here's what that website says:
Mascots, Old and New
Today it's Hey Reb but some at UNLV still remember the first official Rebel mascot -- Beauregard.
Dressed in a gray military field jacket and Confederate cap, Beau is a fanged, winking, black and white cartoon wolf. He came to be because the new school in Southern Nevada wanted to make a little jab at the Wolf Pack mascot of Nevada, Reno.
"UNLV was rebelling against the status quo and the two schools' mascots seemed to mimic the Civil War," said former UNLV president Don Baepler, who is currently director of the Marjorie Barrick Museum of Natural History on campus. "Reno had a northern looking wolf so we wanted a Confederate wolf."
The logo lasted until the early 1970s when a group of black athletes came to Baepler, who was academic vice president at the time, and voiced its displeasure with having a mascot that had a connection with the wrong side of the Civil War.
"They said it didn't feel right playing for a school with such a mascot . . . and I agreed," said Baepler. "Southern Nevada has no real ties to the Confederacy so the change wasn't a big concern."
The student senate voted on a new mascot and the human Rebel logo was born. Initially, a Colonial-like Rebel soldier was the official logo and there was talk at one time of changing UNLV's nickname to Minutemen.
However, the current long-moustached cartoon Rebel known as Hey Reb took hold in the early 1980s and helped the school vault to the top in college apparel licensing within 10 years.
Beauregard may not be prevalent in today's UNLV athletic events but he's certainly not gone and forgotten. The original sketch of the wolf was converted into a mid-court painting for basketball games played in the old University gymnasium. Today, visitors can visit the black, white, scarlet and gray logo circle in its original position at what is now the Barrick Museum, which still uses the existing oak hardwood basketball floor to hold its exhibits.