Kratos is a fictional character and the protagonist of Santa Monica Studio's God of War series, based on Greek mythology and, later, Norse mythology. He first appeared in the 2005 video game God of War, which led to the development of eight additional titles featuring the character as the protagonist. Kratos also appears as the protagonist of the 2010 and 2018 comic series, as well as three novels that retell the events of three of the games. The character was voiced by Terrence C. Carson from 2005 to 2013,[3] with Christopher Judge taking over the role in 2018's continuation, also titled God of War. Antony Del Rio voiced the character as a child in God of War: Ghost of Sparta.

Throughout the Greek era of the series, Kratos is portrayed as a Spartan warrior, who becomes known as the Ghost of Sparta after accidentally killing his family due to the trickery of his former mentor Ares, the God of War. He later avenges the deaths of his family and becomes the new God of War after killing Ares. Kratos is eventually revealed to be a demigod and the son of Zeus, who later betrays him. Kratos embarks on several adventures in attempts to avert disaster or to change his fate. He is usually portrayed as being oblivious to all else and is stoic, bloodthirsty, and arrogant in nature, often engaging in morally ambiguous activities and performing acts of extreme violence. However, he frequently questions himself, undergoes bouts of severe guilt and self-hate, even attempting suicide several times, and is generally portrayed as a tragic figure. Vengeance is a central theme of the Greek era, and installments focus on Kratos' origins and his relationships with his family and the Olympian gods. In the Norse era of the series, Kratos finds himself controlling his rage and learning how to truly be a father and mentor to his son, Atreus, helping him come to terms with his divinity. Along their journey, they combat monsters and gods of the Norse realm, of whom they make enemies, which inevitably leads to the catastrophic battle of Ragnarök.

The God of War franchise is a flagship title for the PlayStation brand and Kratos is one of its most popular characters. The character has been well received by critics and has become a video game icon, a relative newcomer among more established franchise characters, such as Mario, Link, Sonic the Hedgehog, Lara Croft and Crash Bandicoot. The character is now associated with other products and has had various cameos in PlayStation games outside of the God of War series.