This paper explores a simple yet powerful question: If animals are capable of grieving. I began with the theory that certain animals, especially those with strong social bonds like elephants, cetaceans, apes and dogs, might show signs of grief when they lose a companion. To investigate this, I looked at research from different fields, including animal behavior, neuroscience, evolution and even psychology. Focusing on detailed observations across these species, some patterns on how they responded to death repeated themselves, suggesting that animals might be capable of experiencing something similar to grief. Evidence supports the idea that grief is not something exclusive to humans. This paper encourages us to see animals as individuals with complex emotional lives.