Since I haven't read the 'from goblin to goblin god novel', I can only guess. There could be the goblin itself, of course, which is the central character on its journey to godhood. There may be other goblins too, some of whom might be jealous of the protagonist's growth and try to stop it. And perhaps there are some human or elf characters who are initially dismissive of the goblin but later come to respect it as it gains power.
The main characters can include the goblin king's chief enforcer among the goblins, who is responsible for carrying out his orders. Additionally, there could be a young adventurer who stumbles upon the goblin king's realm and becomes embroiled in the power struggles and adventures within the world of the novel.
Well, in the goblin avengers fanfiction, the main characters are probably a diverse group of goblins. There might be a brave goblin warrior who is always ready for a fight. There could also be a goblin inventor or a goblin with the power of persuasion. These characters would come together to form the goblin avengers and face various challenges.
The plot is centered on Goblin Slayer's vendetta against goblins. He is extremely dedicated to this cause. The story shows his adventures in a fantasy world filled with different races and classes of adventurers. He often gets into situations where he has to use his wits and combat skills against the goblins. For example, goblins are known for their devious traps and ambush tactics, and Goblin Slayer has to be constantly vigilant to overcome these and save those in danger from the goblin threat.
Since we don't have much detail, the main characters could be a goblin outcast who falls in love with a popular goblin in their society. Or perhaps it's a goblin warrior and a goblin healer who find love in the midst of chaos and danger.
There's no way to know precisely without reading the novel. However, it might have a young protagonist who is on a quest and has to deal with the goblins on that fateful night. There could also be a wise old wizard or a fearless warrior among the main characters. Maybe there's a goblin with a unique personality who either helps or hinders the other characters during the night - time events.
Since I don't know the specific 'goblin king novel', it's hard to say. But most likely, the goblin king himself is a main character. There could also be his loyal minions or advisers, and perhaps characters from other races like a brave human knight or a wise elf who oppose or interact with the goblin king.
One of the main themes is the fight against evil in the form of goblins. It shows the brutality of the goblin threat and the determination of the Goblin Slayer to wipe them out. Another theme could be survival in a harsh fantasy world where danger lurks everywhere.