lion's share

The greater part or most of something, as in Whenever they won a doubles match, Ethel claimed the lion's share of the credit, or As usual, Uncle Bob took the lion's share of the cake. This expression alludes to Aesop's fable about a lion, who got all of a kill because its fellow hunters, an ass, fox, and wolf, were afraid to claim their share. [Late 1700s]

A disproportionately large segment of the whole: “Though we always divided our winnings, somehow Barton always seemed to end up with the lion's share.”