Someone who engages in war or warlike acts for personal reasons such as: personal fueds, dislike for people of different sexual orientation, re-election, sexual pleasure, or to compensate for a lack of manhood.
1-Adolf Hitler was a Warmonger who encouraged war and violence against non-axis countries.
2-After several anti-Vietnam War demonstrations in America, Warmongers held pro-war demonstrations of their own in support of President Johnson's anti-communist action.