Who is Marcus Brutus from Plutarch's Lives, Volume 2 and what is their importance?

Marcus Brutus was a wealthy Roman senator. At first, he sided with Pompey against Caesar in the civil war, but he was welcomed back by Caesar after Pompey's defeat. Brutus was part of a group who feared Caesar had become too powerful, and who plotted to kill him in the senate. After taking part in the assassination, he fled Rome and raised a military force. Brutus was defeated and took his own life.