The abbreviation TT may mean:

• Tourist Trophy in motorcycle racing
• Table Top (TT scale) in model railroading
• The Atari TT was a computer based on the Motorola 68030 CPU
• Terrestrial Time
• Therapeutic Touch, an alternative medicine practice
• The Audi TT, an automobile produced by Audi in Győr, Hungary.
• Tidningarnas Telegrambyrå, a common abbreviation for Swedish news agency.
• A TT earthing system is one where the customer's earth has no connection to the transformer neutral terminal.
• The IATA code for Air Lithuania
• The ISO 3166-1 alpha-2 Country code for Trinidad and Tobago.
• The ISO 639 Language code for the Tatar language.
• The Truetype font format
• The Transport Tycoon computer game by Chris Sawyer
• Toledo Terminal Railroad
• Time Team, a popular archaeological British TV program on Channel 4
• Trouble Ticket