The sarissa was a pike-like weapon used by Greek phalanxes. It was a remarkable weapon because of its length: 6.3-7 meters. The end was weighted to balance the thing when it was carried by a foot soldier.
Arrian, the historian who traveled with and chronicled Alexander the Great, recorded that the great general created a cavalry armed with sarissas, who were known at the Lancers (Sarissaphaori). Also, in the mosaic at Issus (this is the famous one where Alexander is battling Darius), and on some Greek coins, Alexander is depicted holding a sarissa.
Following Alexander's death, the sarissa fell out of favor because of its extreme unwieldiness; the Byzantine armies revived it for a short time, but not long.