L series may refer to:
- L-series trains in China
- Saturn L series – sedans and station wagons
- L-function
- Honda L engine
- Nissan L engine
- Dirichlet L-function - mathematical functions in number theory
- Rover L-series engine
- Ford L series – trucks
- Canon L lens
- International Harvester L series – trucks
- Lincoln L series – 1920 luxury cars
- Cummins L-series engine
- ThinkPad L series – laptop computers
- Mercedes-Benz L-series truck
- Rolls-Royce–Bentley L-series V8 engine
- Sony Vaio L series – desktop computers
- Subaru Leone
- System Sensor L-Series fire alarm notification appliances
- Artin L-function
- QI (L series), the twelfth series of quiz show QI
- L-Series, a pejorative term for Indian company T-Series