Who does Brutus want to kill?

I'm assuming the Brutus you’re referring to is probably Marcus Junius Brutus, a Roman politician who lived from 85–42 BC. He is most well-known for his role in the assassination of Julius Caesar, which was immortalized in William Shakespeare’s play Julius Caesar. Around 45-44 BC, Brutus joined a conspiracy of senators who feared Caesar’s growing power and possible dictatorship. The conspirators, including Brutus, attacked Caesar in the Senate on the infamous Ides of March (March 15) in 44 BC, eventually killing him.

The famous line “Et tu, Brute?” actually comes from Shakespeare’s play Julius Caesar, and was famously uttered by Caesar as he recognized Brutus among his attackers. There is no evidence that Caesar ever actually said them, though. Shakespeare also sensationalized the “Ides of March” in the same play, giving us the famous line where the soothsayer warns Caesar to “beware the Ides of March.”