Bacteria kill the Martian invaders in H.G. Wells's The War of the Worlds. The Martians defeat humanity's armies and weapons, but they have no natural resistance to Earth's microscopic organisms and die from bacterial infection.
The ending reverses the novel's apparent power balance. Martian tripods carry heat-rays and poisonous black smoke, while human forces seem helpless against their technology. Yet the invaders' bodies are adapted to Mars, not to Earth's biosphere. After their arrival, indigenous bacteria infect them and cause the collapse of the invasion.
Wells described the organisms as “putrefactive bacteria,” connecting the Martians' deaths with decomposition and decay. The novel's narrator observes that the invaders may have been protected from similar diseases on Mars because their advanced civilization had eliminated or escaped many local microbes.
This is not starvation, poison gas or the heat-ray. The heat-ray is one of the Martians' weapons, and it kills humans; it does not destroy the invaders. The conclusion became an early and famous example of biological vulnerability defeating superior technology.