Squanto taught the pilgrims many things. He taught them how to build warm houses, much warmer than those which they stayed in teh first winter. Also he showed them how, when, and where to plant their corn crop so they would have a bountiful harvest in the fall. Swuanto eventually died from a fever in 1622. He was very valuable to the pilgrims, and without him who knows if the colony would have survived.
source: http://www.workersforjesus.com/f25-14.htm
this is a picture of Alvar Nunez Cabeza de Vaca.