Typically, the main character is the one who has been reincarnated as a monster. Their personality might be a mix of their former self's traits and the instincts that come with their new monstrous form.
Another interesting plot could be the power struggles within the monster community. The reincarnated monster might find themselves in the middle of territorial disputes or battles for dominance. They have to use their wits and newfound powers to survive and thrive in this complex and often dangerous new world.
The exploration of a new world is another typical theme. When reincarnated as a monster, the character is in a different world or at least a different part of their original world. They get to discover new magic systems, cultures of other monsters, and hidden secrets. For instance, in many of these novels, the protagonist discovers unique magic spells or abilities that are specific to the monster species they have been reincarnated into.
You might want to check out 'Reincarnated as a Behemoth'. Here, the MC's reincarnation as a monster leads to an exciting and action-packed journey filled with challenges and growth.
One popular title is 'So I'm a Spider, So What?'. In this novel, the protagonist is reincarnated as a spider in a dungeon and has to survive and grow in a harsh new world. Another is 'That Time I Got Reincarnated as a Slime'. The main character is reborn as a slime and gradually builds a powerful nation of monsters.
One of the things that makes these light novels appealing is the character development. When a character is reincarnated as a monster, they usually start from a very weak state. But as the story progresses, they learn new abilities, make allies, and grow in power. In 'Reincarnated as a Dragon's Egg - Let's Aim to Be the Strongest', the dragon starts small but gradually becomes a formidable force. Also, the world - building in these novels is often quite imaginative, with different ecosystems and races designed around the idea of a world where monsters exist.
One popular 'Reincarnated as a Monster' light novel is 'Reincarnated as a Dragon's Egg - Let's Aim to Be the Strongest'. It follows the story of a protagonist who is reincarnated as a dragon egg and has to navigate a world full of challenges and grow stronger. Another one could be 'So I'm a Spider, So What?', where the main character is reincarnated as a spider in a dungeon. The story focuses on her survival and evolution in this new and dangerous form.
Survival is a common theme. When the protagonist is reincarnated as a monster, they often have to fight for their lives in a world that may be hostile. For example, in 'So I'm a Spider, So What?', the spider has to constantly find food and avoid being killed. Another theme is growth. They usually start weak and gradually become stronger through various means like leveling up or evolving.
One popular 'reincarnated monster light novel' is 'So I'm a Spider, So What?'. It follows the story of a girl who is reincarnated as a spider in a dungeon. The story is engaging as it shows her struggles to survive and evolve in a harsh environment. Another great one is 'The Rising of the Shield Hero', where the protagonist is initially treated as a monster by others due to false accusations, and his journey of growth is really exciting.
There's also 'I'm a Spider, So What?'. In this novel, the main character is reincarnated as a spider in a dungeon. She has to struggle to survive in this harsh new environment, using her wits and the skills she develops over time. It has an interesting take on the reincarnation concept as we see the world from the perspective of a spider.