Diminutive of William, from Germanic 'wil-helm' meaning 'resolute protector.'
Willy is a diminutive of William, one of the great names of Western history. William derives from the Old High German Willahelm, a compound of willo ("will" or "desire") and helm ("helmet" or "protection") — meaning something close to "resolute protector." The Normans brought the name to England with William the Conqueror in 1066, and it became so dominant that at certain periods in medieval England nearly one in four men bore some form of it.
Willy emerged as the most affectionate of its diminutives, alongside Will and Bill. The name has accumulated a remarkable range of cultural associations. Willy Wonka, Roald Dahl's eccentric chocolatier, made the name synonymous with whimsy and dark imagination.
Willy Loman, Arthur Miller's tragic salesman in Death of a Salesman, gave it philosophical weight — a meditation on American dreams deferred. Willy Brandt, the Nobel Peace Prize-winning West German Chancellor, gave it statesmanlike dignity. In country music, Willie Nelson has spent six decades making the name feel like a road song and a hand of cards.
Willy fell from fashion in the late twentieth century partly due to its slang associations in British English, but parents willing to overlook that find a name of irresistible charm and warmth. It's the kind of name that ages in all directions — it works on a toddler, a teenager, and a grandfather with equal ease. There is something fundamentally friendly about it.