Lions vs. Porcupines. Lions can bring down wildebeests and giraffes, but when they try to hunt porcupines, the spiky rodents often come out on top. When lions attack porcupines (It's usually young male lions that make that mistake), the porcupine's spines can seriously injure the lion. These injuries can make it impossible for the lions to hunt normally, leading them to hunt livestock or even humans. This study is a deep dive into lion-porcupine interactions over the centuries. Source 6x.
Lions may be the 'king of the jungle' but they certainly cannot win in every situation with specific animals! Porcupines always had a reputation for being particularly dangerous even for humans, unfortunately young lions wouldn't have that knowledge until they attempt for a bite.