Boxer is admired most by the animals. His two slogans are “I will work harder” and “Napoleon is always right.”
In chapter 1 of Animal Farm, the horse Boxer is described as a huge strong horse.
[In] fact he was not of first-rate intelligence, but he was universally respected for his steadiness of character and tremendous powers of work. (ch 1)
Boxer is always a hard worker. Throughout the story, he is the first animal to really buckle down and get things done. He uses his brute strength and work ethic to improve the farm. Even the cynical Benjamin is “devoted” to Boxer.
Boxer represents loyal workers who followed the party line during the Russian Revolution.
No matter what Napoleon says, Boxer supports him. This makes him valuable to Napoleon, who wishes all the animals were like Boxer. In fact, after they send Boxer to his death they tell the others so!