ALEX'S MOBS
One of Minecraft's best known creature expansions, on Fabric.
Alex's Mobs adds a large variety of unique animals, each with distinct behaviors, custom AI, drops, and interactions with the world, fully implemented with models, animations, and sounds, and integrated into biome spawning. The wilds between nations are alive and some of it is dangerous.
The Roads More Travelled adds a gradual erosion system: paths that get walked form over time, so trade routes literally appear in the terrain.