John Peake Knight (13 January 1828 – 23 July 1886) was an English railway manager and inventor, credited with inventing the traffic light in 1868.

Knight was promoted quickly and by the age of 20 had joined the South Eastern Railway, rising to the rank of Superintendent.

Knight's invention was operated by a policeman and used a semaphore system based on railway signalling during the day, and red and green gas-powered lamps at night.

However, in 1869, a gas leak caused one of the lights to explode, badly injuring the policeman operating it, and the system fell out of favour and was removed as a result.

[6] A memorial plaque to Knight's invention can be seen at 12 Bridge Street, Westminster, the corner building close to where the original traffic lights were erected.