Messala is a Roman nobleman and the son of a Roman tax collector; he is also Judah Ben-Hur's boyhood friend and turned into his arch-rival after betraying him. When Messala is reunited with Ben-Hur for the first time in five years, their different views and opinions ultimately end their friendship. Later, Messala betrays his former friend when he accuses of him of attempting to assassinate Valerius Gratus.

Five years later, Judah, having survived the galleys, seeks revenge on Messala for betraying him and his family. Judah offers to drive Sheik Ilderim's chariot intending to defeat his rival. During the race, Messala's chariot breaks apart and he suffers serious injuries.

In the 1959 movie, Messala dies from injuries suffered in the chariot race. However, in the novel, he continues to plot against Judah long after the chariot race despite being crippled and left in financial difficulty. Messala hires a Northman called Thord to kill Ben-Hur, but Thord allows him to live. Upon returning, Thord lies to Messala about killing Judah. Five years later, his mistress, Iras (daughter of Balthasar) murders him - upon learning the true nature of the Romans.

More Info: en.wikipedia.org