This post might be ca. 2050 years late, but let's still discuss Marcus Junius Brutus - yes, that Brutus. Because some of the drama around the assassination of Gaius Julius Caesar stems from Shakespeare's play (the 1953 film adaption is amazing), like the famous quote I used for the title, let's just focus on the essential circumstances.
Brutus to this day is a mostly negative symbol, in Dante's Divine Comedy (which was so influential, it helped establish Tuscan as standard Italian at a time when Italy was split into many dialects) he is being chewed by Satan in the innermost circle of hell as a betrayer of man. Even in Asterix comics, he's depicted far darker and grimmer than what Caesar looks like. The popular association is of Caesar as a brilliant general and legendary ruler, and of Brutus as a regicide. There are plenty of scholarly texts that accept Brutus as a symbol of resistance to tyranny, but the first association "the man in the street" has is that of a traitor.
The reason the whole conspiracy took place was because Caesar installed himself as a emperor-king, which would soon serve as a blueprint for the Roman Emperors starting with Augustus (enabling Nero, Caligula, Caracalla, Elagabalus, etc.) and later for other European dictators, especially in France. Brutus on the other hand was related to Lucius Junius Brutus, one of the founders of the Roman Republic (removing the Etruscan kings) and one of the first senators. Not to say that the Senate was a remotely democratic institution, but it was still closer to our modern ideals than the single hereditary ruler of the emerging Roman Empire. Reducing Brutus' motives to pure patriotism and believe in the Republic would of course be an oversimplification, at least his own and his family's position in the new Rome Caesar created would have been a big worry, but if it hadn't been for the transformation of the political system, there probably wouldn't have been the conspiracy between the (former) senators.
With his crushing defeat at the two Battles of Philippi (Macedonia), the temporary second triumvirate and the gradual installation of Octavian as Imperator Augustus, Brutus' most famous deed was ultimately a failure. Is it because history is written by the victors, that the legacy of Marcus Junius Brutus is that of a betrayer and not that of a vanguard of the republican system that was practically lost during the dark ages?