As a child, my concept of Santa Claus was the Santa in the Coca Cola ads. I wasn't the only one. Many talented artists tackled old Saint Nick over the years, from Thomas Nast to Norman Rockwell, but the modern conception was really created by Haddon Sundblom. Sundblom produced an annual Santa painting for the Coke company from 1931 through 1964. After centuries of gaunt Father Christmas and wizened saints in robes, Sundblom really nailed it.
Cheers to Haddon "Sunny" Sundblom (1899 - 1976), a great American illustrator.