Brutus was certainly not a villain. He had a splendid reputation for integrity in Rome, which was the main reason, at least according to Shakespeare, that Cassius was so anxious to get him to join in the conspiracy. Here is Marc Antony's assessment of Brutus, his enemy, after Brutus committed suicide on the battlefield at the end of the play:
This was the noblest Roman of them all.
All the conspirators save only he
Did that they did in envy of great Caesar.
He only in a general honest thought
And common good to all made one of them.
His life was gentle, and the elements
So mixed in him that nature might stand up
And say to all the world "This was a man."
Whether or not Brutus was a hero is a matter of opinion. It seems to me that both Julius Caesar and Marc Antony displayed more of the conventional heroic qualities. Brutus was primarily a philosopher and did not seem particularly ambitious. There is undoubtedly a great difference between the real Brutus of ancient Rome and the character created by Shakespeare, who depicted him as kind, gentle, thoughtful, and studious.
Brutus says of himself during his quarrel with Cassius in Act 4, Scene 2:
O Cassius, you are yoked with a lamb
That carries anger as the flint bears fire,
Who, much enforced, shows a hasty spark
And straight is cold again.
I don't believe that Brutus can be described either as a villain or a hero.