A third rail is an extra rail used for supplying electricity to trains.
Third rail may also refer to:
- Third rail (model railroading), in rail transport modelling, a technique that is sometimes applied in order to facilitate easier wiring
- The extra rail on a dual gauge railway
- "Third Rail" (song), a 1993 song by Squeeze
- Third rail of politics, a political metaphor
- The Third Rail (magazine), an online magazine about transportation
- The Third Rail (band), an American pop group
- Emergency Third Rail Power Trip , an album by Rain Parade
- Third Rail (TV series), a Singaporean TV drama series
- Third Rail (MLS supporters association), an independent supporters' group for New York City FC
- Third Rail Releasing, a distribution banner of The Weinstein Company
- The Third Rail (album), a 1996 album by Railroad Jerk
- Guard rail (rail transport), used to prevent a train from derailing.
