The Grasshopper is a very popular fairy piece which moves by hopping. Invented by T. R. Dawson in 1912.
A Grasshopper may hop over any unit (friend or enemy) along a Queen-line. It lands on the square immediately after the springboard. This landing square must be free (or contains an enemy unit which is then captured). The Grasshopper is stuck when it has no springboard in sight.
It is depicted as an upside-down Queen, and denoted by G. To illustrate this, consider the following position:
(Black Grasshoppers g4, f6, f8)
Here White is in check by the Gf6. He can answer 1. Kh7 but not 1. Kg8 (because of the Gg4). Similarly, 1. g8=Q is not possible because of the Gf8. On the other hand, 1. g7xf8 answers the check. Further, 1. g7xf8=G+ gives check.
Reader's exercise: How many possible last moves? (I find 28).
In retros with Grasshoppers, the Gs are rarely used to replace other men in the initial position (unlike e.g. Maos). Unless the stipulation states otherwise, they are assumed to result from promotions.