Nemesis is an inverted roller coaster located at the Alton Towers theme park in England. Manufactured by Bolliger & Mabillard, the ride was designed by Werner Stengel in collaboration with attraction developer John Wardley. It opened in the Forbidden Valley area of the park on 19 March 1994.

The 716-metre-long (2,349 ft) ride stands 13 metres (42.7 ft) tall and features a top speed of 81 km/h (50 mph). The four-inversion roller coaster was one of the first Bolliger & Mabillard rides to be installed outside of the United States and the first in Europe as an independent company. Following the 2022 season, the ride is scheduled for a major refurbishment and will be closed until 2024.