A bus driver parked outside Croydon College was left with a gashed head after this suspect forced his way on in the early hours, launching a violent attack.
Officers from the Metropolitan Police's Roads and Transport Policing Command have issued this image of a man they wish to speak to.
The offence took place during the early hours of April 16, last year on a route 75 bus in College Road, Croydon.
At approximately 1.40am the bus driver was carrying out checks on the top deck of the bus - which was not in service - when he heard the doors opening.
He went downstairs to discover a man inside the bus.
The man approached the driver and subjected him to a violent and prolonged assault, before making off in an unknown direction.
The victim was taken to Croydon University Hospital where he was treated for facial injuries, having sustained a large cut to his forehead and several further cuts and bruises to his face and chin.
Anyone with information is asked to contact Detective Constable Anthony Barun, of the Roads and Transport Policing Command, on 07801 203174.
To remain anonymous call Crimestoppers on 0800 555 111.