Beau was a supporting character intended to appear in earlier versions of Tangled. He is notable in that he went through numerous changes throughout the film's production. While Beau ended up on the cutting room floor, he was evidently replaced by Maximus and Pascal, two animal sidekicks who fulfilled Beau's purpose of being supporting characters and comic relief.
Role in the film
Beau's first iteration was that of being Rapunzel's prince in Rapunzel Unbraided. Based on the premise of the original film, Beau would have been somewhat similar to Prince Edward from Enchanted, a prince with flair who was desperately in love with Rapunzel (who at the time was to be voiced by Kristin Chenoweth). An evil witch who despised happy endings decides to pull two humans from the real world, Claire and Vince, who would have replaced Rapunzel and Beau. While Rapunzel is transformed into a squirrel, Beau would have been transformed into a basset hound.
When the film went through a massive plot overhaul into Rapunzel, Beau was repurposed as the pet dog to Bastion, the new leading man and Rapunzel's love interest. He was to be his confident and loyal pet who provided comic relief.