A Grey Heron has mainly pale grey upperparts, a white S-shaped neck with on the lower part a double row of black streaks down the throat, and off-white underparts. Adults have a white head with a slender, drooping crest, as well as a broad black supercilium, i.e. a stripe that starts above the lore (a small area of feathers between the bill and the eye), continues above the eye and ends somewhere towards the back of the head.

In addition, adults have a black shoulder patch, which is absent in juveniles. During flight or when seated, the bird's long neck is retracted in a hunched posture, appearing much smaller than it actually is when standing upright (fig.).