Mazrigos was an orc farseer and leader of the Blackrock Slavers who defended the demon gate which the lich Kel'Thuzad used to commune with the demon lord Archimonde. Arthas and Kel'Thuzad killed him along with four other orcs guarding the demon gate.
Interestingly, Mazrigos's name follows a naming trend common to blue dragons, the ending -gos being shared by numerous dragons including Malygos himself and the prefix Maz- calling to mind Mazthoril, the blue dragons' home in Winterspring. Despite this, however, the orc Mazrigos does not appear to be a dragon or in any way related to the blue dragonflight, and his name is therefore almost definitely coincidental.
As the master of the Blackrock Slavers, Mazrigos was a fierce fighter, using savage tactics to trap and capture victims of his clan. Ignorant of race, Mazrigos captures humans, trolls, gnolls, murlocs or even other orcs. His talent of magic and the elements extended only to a practical level, using his powers when necessary to defeat a threat. He personally fought against the Undead that attacked his base, as he considering them weak and easily destroyed. Eventually falling to their massive numbers his tribe was ravaged and torn apart around him.
One of the realms in World of Warcraft is named after Mazrigos.