The biblical apocalypse had four horsemen, but developers face their own nightmarish quartet! The first horseman, NullPointerException , strikes when you least expect it—trying to use an object that doesn't exist. The second, Segmentation Fault , is that memory-mangling monster that crashes your C/C++ program faster than you can say "core dump." Third comes Merge Conflict , turning your Git workflow into a battlefield of incompatible changes. But the most terrifying horseman? " It works on my machine "—the ghostly specter of environment-specific bugs that magically disappear during demos but return to haunt production. These four harbingers of doom have ended more coding sessions than caffeine crashes ever could!