Sebastian Lang (born 15 September 1979 in Sonneberg) is a former German professional road bicycle racer and time trialist, who rode as a professional between 2002 and 2011. He rode on Gerolsteiner from 2002 until its demise in 2008, and in 2006 became Germany's national time trial champion.

In the 2008 Tour de France, on stage 9, Lang broke from the peloton 22 kilometers into the stage. He shook off his two breakaway companions on the category 1 col de Peyresourde, with another big difficulty to come, the col d'Aspin. He was passed on the latter by Riccardo Riccò, who would win the stage only be excluded from the Tour later on for a positive test to the blood booster CERA. With his long break, Lang earned the most combative award for the stage, and raked in points for the best climber jersey, which he would wear from stages 12 to 14.

In 2011, Lang started and finished all three Grand Tours for Omega Pharma–Lotto, only the 31st rider to achieve this feat. He retired at the end of that season, aged 32.