Whose work first proposed that black holes could exist from Einstein’s equations?

Karl Schwarzschild published the first exact solution to Einstein’s field equations in 1916 while serving in the German army during World War I. The solution described the spacetime around a perfectly spherical, non-rotating mass. It contained a radius now called the Schwarzschild radius, beyond which nothing, not even light, can escape. Although the term black hole came much later, Schwarzschild’s mathematics became central to the concept.