T4 or T-4 may refer to:

Airports and airlines

• Heathrow Terminal 4
• Tiyas Military Airbase, also known as the T-4 Airbase

Biology and medicine

• T4 phage, a bacteriophage
• Thyroxine (T₄), a form of thyroid hormone
• the T4 spinal nerve
• the fourth thoracic vertebrae of the vertebral column
• A non-small cell lung carcinoma staging for a type of tumour
• A CD4 + T lymphocyte
• T4: an EEG electrode site according to the 10-20 system

Entertainment

• T4 (Channel 4), the former daytime teen-aimed slot on Channel 4 in the UK
• Terminator Salvation, sometimes referred to as Terminator 4
• Transformers: Age of Extinction, the fourth film in the live-action Transformers film series

Software and video games

• Text Template Transformation Toolkit, a technology developed by Microsoft
• Tekken 4, a 2001 fighting game

Rail transport

• Eastern Suburbs & Illawarra Line, a Sydney Trains railway service
• Île-de-France tramway Line 4
• T4 (Istanbul Tram)

Vehicles

• Dayton-Wright T-4, a 1918 American light, single-seat reconnaissance aircraft
• Kawasaki T-4, a Japanese aircraft
• Soyuz T-4, a space mission
• Sukhoi T-4, a Soviet aircraft
• Tatra T4, a 1967 Czechoslovakian tram
• Thaden T-4, a 1930s American four-seat all-metal cabin monoplane
• Volkswagen Transporter series IV van
• a model of the OS T1000 train of the Oslo Metro
• Model T4 Cunningham experimental armored car, later the M1 Armored car

Weapons and explosives

• T-4 Atomic Demolition Munition, a small tactical nuclear bomb
• G7e/T4, a Falke German torpedo
• The Italian name for the high explosive RDX

Other uses

• Great East Road, a road in Zambia
• Lockheed Martin's High beta fusion reactor prototype, called T4
• A T4 slip, a tax return form used in income taxes in Canada
• Aktion T4, Nazi Germany's mass-murder of the mentally and physically disabled
• Normal space in topology
• Version 4 of Traveller role-playing game
• T4, one of several fluorescent-lamp formats
• A tornado intensity rating on the TORRO scale
• SPARC T4, a microprocessor introduced by Oracle Microelectronics in 2011

See also

• The Four T's (disambiguation)
• 4T (disambiguation)
• TTTT