* Axolotl (Ambystoma mexicanum): This salamander can regenerate entire limbs, tails, and even parts of its brain and heart. They are particularly fascinating due to their neotenic state, meaning they retain larval features even as adults.
* Planarian (Dugesia japonica): These flatworms can regenerate from incredibly small fragments. If you cut a planarian in half, each half will grow into a complete, new individual. They are even able to regenerate their brains and entire digestive systems!