Hugh, along with his partner Rudolph (his birthday was pre-empted about a month ago here) Ising are responsible for a great deal of the golden age of animation from the 1920's-1940's and beyond.
Though they didn't really create any lasting characters that you would remember today, through their pursuit of furthering the are of animation, they are responsible for creating the venues which would give stage to characters by others.
They began in Kansas City, Missouri working for Walt Disney's Laugh-O-Gram studios and came west with him to California for the formation of "The Disney Brothers Studio". There they worked on the "Alice in Cartoonland", "Oswald the Lucky Rabbit" and "Mickey Mouse" series. Creative/personal/monetary differences with Walt forced them to leave the studio.
It was a ripe time creatively and technologically in the country. The Depression had hit us, so peoples entrepreneurial spirit came to the forefront. Hugh and Rudy produced a pilot film to shop around to the major movie studios, to try and begin an animation department there all their own. The character was Bosko.
And here's that very film...that's Rudolph Ising you see interacting with Bosko.
They sold the cartoon to Warner Brothers and "Looney Tunes" was born. Taking a tip from Walt and his "Silly Symphonies" series it originally was a series of musical cartoons. Here's the very first official "Looney Tunes" based on the popular song of the day "Singin' in the Bathtub" here's "Sinkin' in the Bathtub" with Bosko.
They spent the next couple of years at Warner's also creating the "Merrie Melodies" series. Wanting to expand the technique and appeal of animation, they were constantly squabbling for larger budgets and were let go from Warner's.
They went to MGM and created the "Happy Harmonies" series.
You can see that in the mid to late 1930's, Bosko became a much more realistic character and much more racially offensive by today's standards.
But finally today, historians can acknowledge the influence the boys had...pictured below on Warner's last official Looney Tunes DVD release from 2008...Bosko made the cover along with Bugs Bunny and the rest of the better known characters.
At MGM they also had financial disagreements with the head office and were eventually let go. By this time the studios were all set up with cartoon studios of their own as well as their own producers and directors. Hugh and Rudy faded into the sunset.
But between the boys work at Disney, Warner's and MGM, the stage was set for countless other cartoon characters to come along. Where would Bugs Bunny, Tom & Jerry, Daffy Duck, Porky Pig have played out their comic adventures without the stage that Hugh and Rudy built for them? They didn't create the characters that came after, but they established the forum for them to flourish.