Grey Mare's Tail or Greymare's Tail is the name of several waterfalls:
Scotland Grey Mare's Tail, Galloway Grey Mare's Tail, Kilpatrick Hills Grey Mare's Tail, Kinlochmore Greymare's Tail, Kirkconnel Grey Mare's Tail, Moffat Hills Grey Mare's Tail, Monreith
Wales Grey Mare's Tail, Conwy
See also Marestail (disambiguation)