A sungrazing comet is a comet that passes extremely close to the Sun at perihelion – sometimes within a few thousand kilometres of the Sun's surface. Although small sungrazers can completely evaporate during such a close approach to the Sun, larger sungrazers can survive many perihelion passages. However, the strong evaporation and tidal forces they experience often lead to their fragmentation.

Sungrazer comets were some of the earliest observed comets because they can appear very bright. Some are even considered Great Comets (A great comet is a comet that becomes exceptionally bright). The close passage of a comet to the Sun will brighten the comet not only because the reflection off the comet nucleus when it is closer to the Sun, but the Sun also vaporizes a large amount of gas from the comet and the gas reflects more light. This extreme brightening will allow for possible naked eye observations from Earth depending on how volatile the gases are and if the comet is large enough to survive perihelion.