The God of War series is the story of one man's (often incredibly violent) encounters with the pantheons of ancient Greek and Norse gods. The original run of games saw Kratos gradually kill off nearly every Greek god on Mount Olympus. Hoping for a quieter life following the completion of his vengeance, Kratos settled in Midgard to raise his son, Atreus. Kratos' hope for peace never came to fruition, though, and he's now had multiple run-ins with Norse gods on a quest to spread his deceased wife's ashes at the highest peak in the Nine Realms.
2018's God of War reinvented the series on the gameplay front, but Kratos' inability to avoid violent encounters with deities remains. Compared to the onslaught in God of War 3, Kratos' exploits in the Nine Realms have been rather tame thus far. Kratos hopes he can provide a better life for Atreus, who himself is a Norse god but doesn't effectively operate like one yet. Atreus' true identity is Loki, but God of War's version of the Norse god of mischief isn't necessarily part of the pantheon. Atreus will likely grow into his role as Loki over the course of God of War Ragnarök since it's expected to be the final chapter in Kratos' Norse saga.
There are also many other god-like creatures that are not a part of the pantheon, specifically Jörmungandr, the World Serpent, and the dragons Kratos fights in God of War. Jörmungandr especially is directly involved in the affairs of the gods, and is even prophesied in Norse mythology to fight Thor during Ragnarök, but doesn't quite meet the criteria to be considered a god himself. The Norse gods are split into two camps: the Aesir and the Vanir. The Aesir, who are far more prevalent in God of War's version of Norse mythology, typically relish in their own power and find honor in death through battle. The Vanir appear far more mystical, but can still be prompted to violence.
God Of War: Norse God Known To Kratos - Mimir
Mimir could be considered the most important Norse god in regards to God of War's narrative. He was once closely associated with the Aesir tribe as a servant of Odin, the Allfather. Odin felt that Mimir betrayed him during a conflict with the Giants of Jötunheim, and had Mimir imprisoned atop Midgard's highest peak. As a god of knowledge and wisdom, Mimir was incredibly valuable to Kratos, so the Greek god of war beheaded Mimir, and had him revived. Mimir's severed head will return in Ragnarök to reprise its role as storyteller and confidant, helping Kratos and Atreus through his bountiful knowledge of the gods and realms.
God Of War: Norse Gods Known To Kratos - Freya
Freya is the only Vanir god encountered in God of War and is responsible for reviving Mimir after he was decapitated by Kratos. She is traditionally recognized as a goddess of love and possesses great foreknowledge in Norse mythology, which deals heavily in prophecies. For most of God of War, Freya has an uneasy alliance with Kratos, who is distrustful of all gods. Using the moniker Witch of the Woods, Freya kept her identity as a god and ex-wife to Odin a secret, which enraged Kratos. His anger was returned by Freya after he killed her son Baldur, the inciting incident to her attack on Kratos in the Ragnarök trailer.
God Of War: Norse Gods Known To Kratos - Baldur
Baldur is the son of Freya and Odin, Aesir god of light according to Norse Mythology. He's also the main antagonist in 2018's God of War. He first encounters Kratos when searching for the guardian of the Giants that remained hidden in Midgard - Kratos' recently deceased wife, Faye. Baldur mistook Kratos for the Giant and attacked, though Kratos momentarily bested him.
Baldur is estranged from Freya due to a spell she cast on him to prevent his prophesied needless death. The spell makes Baldur effectively invincible but comes with a side effect that inhibits all sensations. Atreus broke the spell with a mistletoe-laden arrow, and Baldur was subsequently slain by Kratos.
God Of War: Norse Gods Known To Kratos - Magni & Modi
Magni and Modi, Aesir demigods of strength and bravery, are the sons of Thor, and grandchildren to the Allfather. They are half brothers, having different mothers, and join Baldur on his search for Kratos and Atreus. In Norse mythology, Magni and Modi are prophesied to be two of the few who survive Ragnarök, and inheritors to their father's hammer, Mjolnir. Kratos' presence in the Nine Realms has had adverse effects on prophecy, though, bringing about Ragnarök early, and killing Magni by embedding God of War's signature Leviathan Axe in his skull. Modi escapes the first encounter, but confronts the father/son duo two more times, with the third meeting ending in his death at the hands of Atreus.
God Of War: Norse Gods Known To Kratos - Thor
Kratos hasn't technically met Thor, the Aesir god of lightning, but his appearance in God of War is worth noting. Players are never given a good look at him, only his hammer, but Thor confronts Kratos and Atreus at their home in a post-credits scene. The sequence is played off as Atreus' dream but is heavily implied to be a prophetic vision. This is seemingly confirmed by Thor's appearance in Ragnarök's trailer. Thor is presumably on a quest to avenge the deaths of his sons and half-brother, and will likely be a primary antagonist in Ragnarök.
Until the events in God of War, Kratos managed to lead a fairly quiet life in Midgard, never attracting the attention of the gods. Killing a select few members of the pantheon and bringing about a premature Ragnarök has brought him unwelcome attention, though, and he will soon be meeting many more of the Norse gods. Thor will presumably be officially introduced, and Kratos is shown meeting Tyr in the Ragnarök trailer, but since the sequel is confirmed to be Kratos' final traipse through the Nine Realms, Odin is expected to make an appearance as well. Of all the Norse gods Kratos has officially met, more than half have ended up dead, which is about par for the course in God of War.