Without a doubt, the most badass part of Gladiator is the scene where Maximus reveals himself to Commodus and the tens of thousands of screaming fans in the Coliseum.
Crowe and Ridley Scott spent a long time planning that particular line and even had as many as 20 different versions of it before they decided on the final version seen in the movie.
During the commentary on the extended version of the movie, Russell Crowe explained none of what Maximus said during his “Father to a murdered son, husband to a murdered wife” speech would work if no one totally believed in what they were doing and so a lot of work had to go into making that scene pop.