Montag is the protagonist; he is the character meant for the audience to feel sympathetic towards. His role in the story is certainly heroic from an individual viewpoint; he stands up to the oppression of government control and becomes an individual, a person capable of rational and independent thought instead of parroting non-ideas from television. However, Chief Beatty also acts heroically from the viewpoint of society and the government; although he is a hard man, he is doing what is necessary to keep their way of life intact.
"Read a few lines and off you go over the cliff. Bang, you're ready to blow up the world, chop off heads, knock down women and children, destroy authority. I know, I've been through it all."
(Bradbury, Fahrenheit 451, Google Books)
In Beatty's view, the society works, and it works because the common man is kept ignorent and unthinking; his actions, to the point of allowing Montag every opportunity to give himself up, are almost selfless. He even dies a "hero," trying to take a criminal to justice. Although his actions are not sympathetic to the reader's viewpoint, he is still a man of resolve, using every weapon at his disposal -- even illegal book-knowledge -- to do what he felt was right.