Stephenson 2-18 (St2-18) is a massive red supergiant star located in the Cygnus constellation, approximately 19,570 light-years away. It boasts a radius about 2,150 times that of the Sun and a mass around 30 times greater. With a surface temperature of 3,200 to 3,500 Kelvin, it is cooler and redder. St2-18 will eventually shed its outer layers and explode as a supernova, offering valuable insights into stellar evolution and enriching the interstellar medium.