It was the Powhatan tribe which helped the pilgrims survive through their first terrible winter. The new settlers weren't use to working the kind of soil they found in Virginia, so they were unable to grow enough crops to feed themselves. Without any emergency supplies from England, and facing a harsh, desperately cold winter, the settlers began to starve. That more people didn't suffer was down to the assistance of the Powhatan, who provided the settlers with food, and even more crucially, expertise on how to grow crops.
Unfortunately, the Jamestown settlers didn't return the favor, still seeing the natives, despite the help they'd provided, as heathen savages occupying land which they believed rightfully belonged to them by the grace of God. This attitude of racial superiority, manifested in increasingly brazen incursions into Powhatan territory, led to a full-scale war between the English settlers and the Powhatan, which claimed many lives.