A Thorne-Żytkow object (TZO or TŻO) is a theoretical star type consisting of a giant star with a neutron star as its core. It would result from a neutron star colliding with a red giant or supergiant. If the two come into contact, drag could bring the neutron star to the center, sometimes after a phase with the neutron star within the giant star's envelope, orbiting the giant star's core. It is assumed such a TZO would be a phase, perhaps leading to a more conventional neutron star with an accretion disk.
No observations are generally accepted, but candidates have been found, such as the star HV 2112 in 2014.