Short form of Leonard, from Germanic 'leon-hard' meaning brave as a lion.
Len is the pared-down soul of Leonard, stripping away all ceremonial weight to leave something clean and direct. Leonard itself comes from the Old High German leon (lion) and hard (strong, brave) — a name meaning essentially lion-hearted, which gave it enduring appeal from the early medieval period onward. Saint Leonard of Noblac, the 6th-century French hermit who became the patron saint of prisoners and expectant mothers, anchored the name firmly in Catholic Europe for centuries.
As a standalone name, Len carries the flavor of mid-20th-century American and British working life. Len Deighton, the British espionage novelist whose unnamed cockney spy antedated James Bond in attitude if not fame, gave it a sardonic intelligence. Len Bias, the electrifying University of Maryland basketball player whose death by cocaine overdose in 1986 — the night after being drafted second overall by the Boston Celtics — turned his name into a tragedy that changed American drug policy.
Len Cariou, the Tony Award-winning stage actor, showed the name could carry genuine gravity. What Len does best is disappear into the person wearing it. It makes no demands on the imagination.
Len is the guy who fixes the boiler, writes the novel, coaches the team, or wins the Nobel — and the name simply steps aside and lets him do it. Its very brevity is a kind of confidence. In an era of maximalist naming, Len's restraint has begun to feel quietly radical.