Yes, in one sense you probably could. If you think about the classical definition of a hero as given by Aristotle, Brutus fits the bill in many ways. He is a man of high status in a responsible position, with a good deal of authority. He has great talents and noble qualities: in fact after his death Mark Antony describes Brutus, not Caesar, as "The noblest Roman of them all."
Other signs of a classic tragic hero are that he should essentially bring about his own destruction, and that he should be brought down by a flaw in his own character, rather than by outside circumstances. Of course it is debatable whether Shakespeare really presents Brutus as having a "tragic flaw" since he joins in the conspiracy against Caesar only from the highest motives. But he is certainly brought down mainly by his own actions, so in this respect he can also be considered a tragic hero.
Finally, others, such as his family and followers, are also involved in his fate; a further typical mark of a tragic hero.
Other signs of a classic tragic hero are that he should essentially bring about his own destruction, and that he should be brought down by a flaw in his own character, rather than by outside circumstances. Of course it is debatable whether Shakespeare really presents Brutus as having a "tragic flaw" since he joins in the conspiracy against Caesar only from the highest motives. But he is certainly brought down mainly by his own actions, so in this respect he can also be considered a tragic hero.
Finally, others, such as his family and followers, are also involved in his fate; a further typical mark of a tragic hero.