When Wellington Mara bought them from a bookie who was leaving NYC for health reasons in the early 1930's they were called the Titans.
At their stadium were ten foot high letters spelling the name.
Mara asked a contractor to think up a new name using as few new letters as posible.
His candidates, requiring one new letter each, were the Saints and the Giants.
Since the Mara's were devout Catholics, the name Saints, way back then, was considered blasphemous!
Thus the New York Giants were born.