Max the Dog is The Grinch's dog and one of the main characters in the computer animated Dr. Seuss' The Grinch. He'll voiced by the famous actor who voiced random characters, Frank Welker.
Instead of a frightened, timid dog who reluctantly does the Grinch's bidding, Max is very much loving and loyal to the Grinch unlike his previous version. He's very different than his 1966 and 2000 version.
Max is seemingly smarter than the average canine, almost acting as the Grinch's "butler" of sorts. At one point, Max does this in an attempt to sleep in the Grinch's bed, but The Grinch doesn't buy it.
Then the Grinch's moose companion Fred does the same thing and the Grinch relents which he immediately regrets this.
He also doesn't like it when his master was being mean to Cindy Lou Who and the people of Whoville, but he knew that his master have a good heart somewhere.
Like his previous version, it's still unknown where he and The Grinch met during childhood or what. But he have been living with his master for 53 years.