Massive stars are born from giant molecular clouds along with many lower mass stars, forming a stellar cluster or association. They dominate the pressure of the interstellar gas through their strong UV radiation, stellar winds and, ultimately, supernova explosions at the end of their life. These processes help the formation of the next generation of stars, but this trigger of star formation is not yet well understood. The Carina Nebula is one of the youngest, most active sites of massive star formation in our Galaxy. In this nebula, we have discovered a bright X-ray source that has persisted for ∼30 years. The soft X-ray spectrum, consistent with a kT∼128 eV lackbody with mild extinction, and no counterpart in the optical and infrared wavelengths indicate that it is a 106 year-old neutron star. Current star formation theory does not allow the progenitor of the neutron star and the other massive stars in the Carina Nebula (in particular η Carinae) to be coeval. This result suggests that the Carina Nebula experienced at least two episodes of massive star formation. The neutron star may be responsible for part or all of the diffuse X-ray emission which permeates the Nebula.