Grimms are legendary in multiple Multiverses. Revered as warriors throughout the cosmos. Around 2,000 years ago in the present time, there was once a clan of Grimms hidden from Israelite history. Sometime after the last Judge died, their families soon inherited their abilities similar to how when a patriarch or matriarch becomes a Stand-User, the rest of their family become Stand-Users, being connected by otherworldly threads. They became a clan of warriors who traversed the Omniverse via Mount Sinai of each world, where the Ten Commandments in all worlds are heavily protected and buried. They invented a triangular portal device that they used to travel across worlds, which I learned how to build through the great mind that reverse-engineered the device: Stanford Pines.
There are several weak points on Planet Earth in several universes that allow for easier Boom Tube access. New York, L.A., San Diego (United States), San Diego (Philippines), The Devil's Palms, the Wall Eyes, Burnham, Morioh, Tokyo, Gravity Falls, Seattle, Wartwood, Newtopia, The Boiling Isles, Portland, Mewnie, Beach City, Hong Kong, London, Iceland, Denmark, Gotaland, and the two Poles. Interestingly enough, these areas have the most supernatural anomalies that have yet to be researched on. These are where these Grimms lived.
They say that there was once a Grimm who killed a Saiyan known as Kankon. When he first heard of Earth, he went to the planet to try and invade it. The Grimm, known as Celeste Vinticore, was taking care of a Wesen Uprising in the 15th Century, with Blutbaden, Hexenbiests, Damonfuers, Hundjagers, and Reinigen running around killing and eating people. Each variant did the exact same thing, which was rather eerie. They all strategically defeated the Saiyan by tricking him into having dinner with them. They all proceeded to kill the Saiyan when he slept. Pulling their tail and decapitating the Saiyan. They soon dissected and studied its parts, finding out that the Wesen known as the Wildermann have the same bone structure and body figure as the Saiyans.
They say there was also another Grimm who was a terrible serial killer. He killed several Wesen in Portland, Oregon, not caring whether or not they are innocent or pleaded guilty. He was argued to be an Endezeichen Grimm. His name was Johann Pines: A possible ancestor or distant relative of Stanford Pines. He lived in the 19th Century in Portland, Oregon. He was a serial killer, yes, but he did in fact study those he kills, dissecting each of them. One day, he was tasked to kill what is known as an "Aztec Deity" who visited Mexico and went on to become someone similar to a god to the Mexican slaves. He went on to investigate and ransacked the creature's ship. Using a microscope, he took some of the creature's dandruff and found out that the skin never dies, unless, he places the Kryptonite near it. So, he created an arrow with a Kryptonite tip and proceeded to kill the so-called "god." He took its body and cut it to pieces with a blade formed from Kryptonite, proceeding to study the alien in secret. He found out that when Kryptonite was close to the creature, the material glows green.
A New God known as Ralabak fell to Earth one day in the 6th Century. A Grimm by the name of Beowolf killed the New God, mistaking it for the Siegebarste known as Grendell (who he successfully killed later on), killed it with a Hammer he created from the Radion in its ship. In hindsight, these aliens should stop carrying their weaknesses on their ship... He learned that Siegebarstes are closely related to Apokoliptians, studying their bones.
Later on, a Grimm Demigod by the name of Amleth who lived in the 10th century was somehow given a Radion Dagger, a part of Beowulf's collection of weapons. He battled the horrid Asgardian, his Uncle, Fjolnir the Brotherless, and proceeded to kill him, his traitorous mother, his foolish younger brother, and Fjolnir's entire family. He soon was resurrected after his death and is now known as a powerful Old God. He later killed the Olympian known as Thanatos with the same dagger during a skirmish in a war between the Olympians and the Asgardians.
There are other Grimms. There was one who ended a war between Humans and the Black Claw and then killed Zerstorer, son of Lucifer, the following year. Once, a Grimm wrote two books that caused a massive rebellion. His descendant created the Hellsing Organization. His son defeated Stefan, for a while. And his daughter saved the world a couple of times now from a being known as Bill Cipher. But technically, she just gave themselves more time. Because we're coming, Gabrielle JoJo... We are coming...