Leiningen is a fictional character from the short story "Leiningen Versus the Ants," written by Carl Stephenson. He is a determined plantation owner in the Brazilian jungle who faces a massive invasion of aggressive ants threatening his land and workers. In the story, Leiningen's resourcefulness and bravery are tested as he devises a plan to protect his plantation. His character embodies themes of human resilience and the struggle against nature, showcasing the conflict between man and the environment.