Near-Earth asteroids (NEAs) are bodies whose orbits bring them within 1.3 AU of the Sun, crossing or approaching Earth's path. The ten largest known NEAs — from 1036 Ganymed (about 34 km across) down to 4179 Toutatis — orbit among the inner rocky planets whose gravity they repeatedly encounter on planet-crossing paths. Ganymed is the largest NEA discovered, yet even it poses no imminent threat. These objects are scientifically valuable: they may be extinct comet nuclei or fragments of larger main-belt bodies, and studying their orbits helps refine impact hazard assessments and test planetary defence strategies.