The Titan from Destiny could also be a main character. Their strength and tank - like abilities would be useful in the often - chaotic battles against goblins. Paired with the Goblin Slayer, they could form a front - line force that would be hard to break. And if we consider some of the non - human characters in the Goblin Slayer world, like the Dwarf, they could also play a significant role in the crossover, perhaps providing unique weapons or technology that could be useful in the fight against both goblins and Destiny's enemies.
Obviously, the Goblin Slayer himself would be one of the main characters. From Destiny, the Guardian, especially a Hunter with their stealth and agility, could be a great match. The Hunter's ability to quickly dispatch enemies and traverse difficult terrain could complement the Goblin Slayer's more brute - force approach when it comes to goblin - slaying.
One possible plot could be that the Guardians from Destiny are called to the world of Goblin Slayer due to some strange energy anomaly. They team up with the Goblin Slayer to fight against an army of goblins that have been enhanced by a Darkness - like power. The Guardians' advanced technology and powers would make for an interesting contrast with the more medieval - style combat of the Goblin Slayer.
The Goblin Slayer himself would definitely be one of the main characters. And perhaps Luke Skywalker from Star Wars could be another. Luke's Jedi skills and the Goblin Slayer's goblin - slaying expertise could create an interesting dynamic.
If it's a crossover with 'Naruto', Naruto Uzumaki would be an interesting character to pair with the Goblin Slayer. Naruto's positive attitude and his powerful ninja skills could complement the Goblin Slayer's more serious and direct fighting style. They could work together to protect a village that is being attacked by goblins. Also, in a crossover with 'One Piece', Luffy could be paired with the Goblin Slayer. Luffy's determination and his ability to lead his crew could be useful when they are facing a large group of goblins.
It could be a powerful demon lord from the Doom universe that has possessed a goblin king in the Goblin Slayer world. This combined entity would have the cunning and numbers of the goblins along with the raw power and dark magic of the demon lord. It would be a formidable foe for the Doom Slayer and Goblin Slayer to face.
One possible plot could be that the Doom Slayer is somehow transported to the world of Goblin Slayer. He then teams up with Goblin Slayer to take on an especially powerful horde of goblins that have been corrupted by demonic forces from Doom. Their combined skills in combat, the Doom Slayer's superhuman strength and arsenal, and Goblin Slayer's knowledge of goblin tactics would make for an epic battle.
In a crossover with 'Attack on Titan', Eren Yeager could be an interesting addition. His determination and ability to transform into a Titan could be used in tandem with the Goblin Slayer's tactics. They could face off against goblins that have somehow made their way into the walls, or maybe even goblins that have been experimented on by the same people who created the Titans.
One interesting aspect could be the contrast in their fighting styles. The Goblin Slayer is more methodical and strategic when dealing with goblins, using his knowledge of their habits. The Doom Slayer, on the other hand, is a force of pure destruction. In a crossover, perhaps they could learn from each other. The Goblin Slayer could pick up some of the Doom Slayer's more aggressive tactics, while the Doom Slayer might gain some strategic thinking from the Goblin Slayer.
There could be a cultural clash. The Doom Slayer comes from a more futuristic and hellish setting, while the Goblin Slayer is in a medieval - ish fantasy world. Their ways of communicating and understanding the world are different. However, this could also lead to some interesting exchanges. For example, the Goblin Slayer might be fascinated by the Doom Slayer's energy - based weapons, and the Doom Slayer could be intrigued by the magic and alchemy in the Goblin Slayer's world.
High Elf Archer is another important character. She is a skilled archer with a somewhat haughty personality. She joins the Goblin Slayer on his quests, and her interactions with the other characters, especially her banter with the Goblin Slayer, are quite interesting.
The main character is obviously the Goblin Slayer. He's the one leading the fight against the goblins.