(biblical) Four beings in Revelation 6:1–8 that bring about the Apocalypse, each embodied as a horseman riding a different-colored horse that represents a different aspect of the Apocalypse.
"This is a graph of the death rate from infectious disease in this country. The heroes of my field have slain one of the Four Horsemen of the Apocalypse. While the heroes of your field gathered in the desert to create a new one."
(idiomatic)Harbingers of doom; several signs which combine to imply the imminence of literal or figurative destruction.
2008, Shayna M. Steinfeld, Bruce R. Steinfeld, The family lawyer's guide to bankruptcy: forms, tips, and strategies, page iii:
Four Horsemen of the Apocalypse,... Here and now those dread specters are: Divorce, Illness, Unemployment and Overspending. These are now the harbingers of economic doom […]
2006, Ronald Brian Adler, Lawrence B. Rosenfeld, Russell F. Proctor, Interplay: the process of interpersonal communication, page 305:
[One authority] has identified four types of communication, which he calls the "Four Horsemen of the Apocalypse," that are signs of a marriage having problems […]