T5 or T-5 can mean:

• Turkmenistan Airlines, IATA airline designator
• A kind of topological space, see Normal space
• A type of high output fluorescent lamp with an external diameter of 5/8th of an inch
• T5 spinal nerve
• T5 - Tele5 - Polish TV channel of the Polcast Television
• Fifth thoracic vertebra of the vertebral column, in human anatomy
• Taylor T5 Thinline Fiveway (acoustic/electric guitar)
• Telecinco, Spanish TV station
• Thunderbird 5, one of the rescue vehicles in the series Thunderbirds
• The designation of the series V Volkswagen Transporter van
• The high-performance T5 engine used in T5 model Volvo cars.
• Palm, Inc.'s Tungsten T5 Palm OS-based PDA .
• Trikke 5, 3 wheeled cambering vehicle
• T5 Network Connection A type of network connection