Werner Stengel (born 22 August 1936) is a German roller coaster designer and engineer. Stengel is the founder of Stengel Engineering, also known as Ingenieur Büro Stengel GmbH.
Born 22 August 1936, in Bochum, Germany, Stengel first worked on amusement park rides in collaboration with Anton Schwarzkopf in 1963. He established his own company, Stengel Engineering, in 1965. His collaboration with Schwarzkopf was responsible for many innovations in roller coaster design, including in 1975 the first modern looping coaster - Revolution at Six Flags Magic Mountain. His clothoid loop is now standard on many roller coasters as it produces less intense forces on the human body than a circular vertical loop. In 1976 Stengel and Schwarzkopf established the first horizontal launch "Shuttle Loop". Stengel is also noted as being a pioneer in heartlining, the principle of having the track twist around the heartline of the rider, rather than the center of the track rotating itself.