13 million dead:

    All Punic Wars: 1.0M
    Gladiators: 1.0M
    Slave Wars (Servile Wars): 1.0M
    Cimbri-Teutoni War: 0.3M
    Social War: 0.3M
    Mithridatic Wars: ca. 0.5M
    Gallic War: 1.0M
    Juleo-Claudian Paranoia: 0.028M
    Jewish Wars: 0.4M
    Boudica's Revolt: 0.15M
    Decline and Fall: 7.0M
    TOTAL: over 13.0M

Source: http://necrometrics.com/romestat.htm

To be fair, that is over almost 1000 years. 13,000 per year is less than how many die each year in Mexico due to drug violence, and much less than the Syrian Civil war.

It's a Monty Python reference. /sigh