The Leyland Lion (B21) was a bus chassis made by Leyland Motors.

It was known as the Leyland Lion or Leyland B21 depending on the markets. This bus was produced in small numbers from 1981 to 1985 and built exclusively for export. The base of the chassis was the Leyland National and completed with components of the Bristol RE.

The engine was a turbocharged O.510 six-cylinder diesel engine from Leyland with a displacement of 8.3 liters. The alternative was a diesel engine, the 671GM from Detroit Diesel in conjunction with an automatic transmission.

Overall, only 69 chassis were manufactured. They were configured as buses with 41-45 seats.