Thanos

Thanos, is a powerful warlord who rules over a small distant region of space and commands a massive army known as the Chitauri. He allied himself with Loki to invade Earth and with Ronan the Accuser to destroy Xandar. His main objective is to obtain the Infinity Stones, so he can become unbeatable in warfare.

Rise to Power
Thanos built up a reputation of a brutal unmerciful warlord, he conquered a region of space and took control of a large army of the Chitauri, eliminated the Zehoberei race and butchered anyone who defied him.

He often kills those who stand against him and if they have children, he sometimes spares them and raises them under cruel circumstances to serve him two of these children Gamora and Nebula he referred to as his "daughters"