| The Spaceship Company | business | Mojave | 2005 |
| The Stone Quarry | business | Pasadena | 2004 |
| The Travelers Companies | business, enterprise, public company | New York City | 1853 |
| The Trump Organization | business, enterprise | Trump Tower | 1923 |
| The University of Texas MD Anderson Cancer Center | hospital, public educational institution of the United States, university | Houston | 1941 |
| The Vanderpump Hotel Las Vegas | hotel | — | March 2, 1979 |
| The Viper Room | pub, business, nightclub, music venue | California | 1993 |
| The Wharton School | business school, private university | Philadelphia | 1881 |
| Theodore Roosevelt Island | river island, plantation, National Memorial of the United States | — | May 21, 1932 |
| Thermos L.L.C. | manufacturing company | Chicago, Minato | 1980 |
| ThinkFilm | film industry, film production company, film distributor | New York City | September 2001 |
| Thinking Machines Corporation | business, enterprise | Carter's Ink Building | 1983 |
| Thinking Machines Lab | business | — | 2025 |
| Thiokol | business, defunct organization | Trenton, Brigham City | 1929 |
| Thomas Jefferson University | private not-for-profit educational institution, university | Philadelphia | 1824 |
| THQ | video game publisher, video game developer, public company | Agoura Hills, California | 1990 |
| Thrustmaster | business | Hillsboro | 1990 |
| THX | technical standard, business | San Rafael | 1983 |
| Tiffany & Co. | jewelry shop chain, business, public company | New York City | 1837 |
| Tiger Electronics | business, subsidiary company | Vernon Hills | 1978 |
| Tiger of Sweden | business, brick and mortar | Stockholm | 1903 |
| Tilted Mill Entertainment | video game developer | Framingham | 2001 |
| Timely Comics | comics publishing company, business | Manhattan | 1939 |
| TiVo Corporation | business, enterprise, public company | Santa Clara, San Jose | 1983 |
| TJX Companies | business, enterprise, public company | Framingham | 1956 |
| TNT | production company, specialty channel, subscription television | Atlanta | October 3, 1988 |
| TopCoder | business, enterprise | San Francisco | 2001 |
| Touchstone Pictures | film production company | Burbank | February 15, 1984 |
| Towson University | public educational institution of the United States, university | — | 1866 |
| Toys "R" Us | toy store chain, baby goods shop, clothing store chain | Wayne | 1948 |
| Toys for Bob | video game developer | Novato | 1989 |
| Trans States Airlines | airline | United States, Bridgeton | 1985 |
| Trans World Airlines | airline | Fort Worth | 1926 |
| Treasure Island Hotel and Casino | skyscraper, casino, hotel | — | 1993 |
| Trek Bicycle Corporation | bicycle manufacturer, business | Waterloo | 1976 |
| Triangle Film Corporation | film production company, film studio | Culver City | July 11, 1915 |
| TriBeCa Productions | television production company, film production company | New York City | 1989 |
| Trident Microsystems | business, enterprise, public company | Santa Clara | 1987 |
| Trilith Studios | film studio, studio | Fayette County | 2014 |
| Trimark Pictures | film production company, business | Santa Monica | 1985 |
| Trimble | business, enterprise, public company | Westminster | 1978 |
| Trinity Washington University | private not-for-profit educational institution, university | Washington, D.C. | 1897 |
| Tripadvisor | travel website, website, business, enterprise, public company | Needham | February 14, 2000 |
| Tripwire Interactive | video game developer | Roswell | 2005 |
| TriStar Pictures | film production company | Culver City | 1982 |
| Troika Games | video game developer, organization | Irvine | 1998 |
| Troubadour | nightclub | — | 1957 |
| Trump International Hotel and Tower | skyscraper, hotel | — | 2009 |