Heavy leptons are hypothetical particles that are similar to standard model leptons (such as electrons, muons, and neutrinos) but with much greater mass. These particles are predicted by some extensions of the standard model of particle physics, such as theories that include extra dimensions or new symmetries. Heavy leptons are of interest to physicists because their existence would provide evidence for physics beyond the standard model. Detecting heavy leptons would also help to explain mysteries such as the origin of dark matter and the imbalance between matter and antimatter in the universe. Experimental searches for heavy leptons are ongoing at particle colliders such as the Large Hadron Collider (LHC) at CERN. If heavy leptons are discovered, it could revolutionize our understanding of fundamental particles and forces in nature.