Bartosz Zmarzlik is a Polish motorcycle speedway rider, a four-time World Champion, three-time World Team Champion, World Junior Champion (2015) and European Junior Champion (2012). He is the third Polish rider in history, after Jerzy Szczakiel and Tomasz Gollob, to win an individual World Championship title.

Motorcycle speedway, usually referred to simply as speedway, is a motorcycle sport involving four and sometimes up to six riders competing over four anti-clockwise laps of an oval circuit. The motorcycles are specialist machines that use only one gear and have no brakes. Racing takes place on a flat oval track usually consisting of dirt, loosely packed shale, or crushed rock. Competitors use this surface to slide their machines sideways, powersliding or broadsiding into the bends. On the straight sections of the track, the motorcycles reach speeds of up to 70 miles per hour (110 km/h).