Marcus Junius Brutus was a Roman senator. He was a character in William Shakespeare's play Julius Caesar, set on Earth during the end of the Roman Republic. He was a close friend of the play's namesake, but ultimately betrayed Caesar.
Elim Garak once claimed that he would have been most, rather than least, suspicious of Brutus had he been in Caesar's place, but according to Doctor Bashir Caesar's inability to suspect treason from Brutus was what made it a tragedy. (DS9: "Improbable Cause")