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 Escherichia virus T4 is a species of bacteriophages that infect ''Escherichia coli'' bacteria. It is a double-stranded DNA virus in the subfamily '' Tevenvirinae'' from the family Myoviridae. T4 is capable of undergoing only a lytic lifecycle ...

, a bacteriophage * Thyroxine (T₄), a form of thyroid hormone * the T4

spinal nerve A spinal nerve is a mixed nerve, which carries motor, sensory, and autonomic signals between the spinal cord and the body. In the human body there are 31 pairs of spinal nerves, one on each side of the vertebral column. These are grouped into th ...

* the fourth thoracic vertebrae of the vertebral column * A

non-small cell lung carcinoma staging Non-small-cell lung cancer (NSCLC) is any type of epithelial lung cancer other than small-cell lung carcinoma (SCLC). NSCLC accounts for about 85% of all lung cancers. As a class, NSCLCs are relatively insensitive to chemotherapy, compared to sm ...

for a type of tumour * A

CD4 In molecular biology, CD4 (cluster of differentiation 4) is a glycoprotein that serves as a co-receptor for the T-cell receptor (TCR). CD4 is found on the surface of immune cells such as T helper cells, monocytes, macrophages, and dendritic ...

+ 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 __NOTOC__ The Dayton-Wright T-4 Messenger was a light, single-seat reconnaissance aircraft built in the United States by the Dayton-Wright Company in 1918 in the hope of gaining a production contract from the United States Army. It was a small con ...

, 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