- Taco Bell – named after founder Glen Bell.
- TAG Group (Holdings) S.A. – Luxembourg-based holding company named from Techniques d'Avant Garde
- TAG Heuer – watch-maker named after Edouard Heuer, who founded Uhrenmanufaktur Heuer AG in Switzerland in 1860. It was taken over by TAG Group (Holdings) S.A. in 1985 and branded TAG Heuer in 1999. It is now owned by the LVMH (Louis Vuitton Moët Hennessy) conglomerate.
- Talgo – from "Tren Articulado Ligero Goicoechea-Oriol" (Spanish for "Goicoechea-Oriol Light Articulated Train"), Goicoechea and Oriol being the founders of the company.
- TAM Airlines – named from Transportes Aéreos Marília (Marilia's Air Transport). Marília is a city in São Paulo state, Brazil.
- TAP Portugal – from "Transportes Aéreos Portugueses" (Portuguese Air Transport).
- Taser International – named after a fictional weapon, Thomas A. Swift's Electric Rifle, after the novel Tom Swift and His Electric Rifle by Victor Appleton. The company was incorporated in Arizona in 1993 by brothers Rick and Tom Smith as Air Taser, Inc.).
- Tata Group – conglomerate named after Jamshedji Tata, considered "the father of Indian industry".
- Taxan – made-up name chosen partly because Takusan is a Japanese word for many or much and was considered propitious, but mainly because the head of the company, in the U.S. at the time, Tak Shimizu was known by everyone as Tak-san.
- TCBY – Originally, the company's name was "This Can't Be Yogurt", but a lawsuit from a competitor named "I Can't Believe It's Yogurt!" forced TCBY to create a new backronym for its initials: "The Country's Best Yogurt".
- TCL – from Today China Lion. Derived from literal translation of "今日中国雄狮" from Chinese to English.
- TCS – from Tata Consultancy Services, from India's Tata Group, named after founder and legendary industrialist Jamshedji Tata.
- TDK Corporation – from Tokyo Denki Kagaku (Tokyo Electronics and Chemicals).
- TEPCO – Tokyo Electric Power Company
- Tesco – founder Jack Cohen – who sold groceries in the markets of the London East End from 1919 – acquired a large shipment of tea from T. E. Stockwell. He made new labels by using the first three letters of the supplier's name and the first two letters of his surname.
- Teva Naot – outdoors shoe company is named after the modern Hebrew word for 'nature' (pronounced "tehvah")
- Texaco – from The Texas Company U.S.A.
- THX – from Tomlinson Holman Crossover, the name of the technology's inventor and the audio technology of a crossover amplifier. It may be a backronym, as the technology is owned by George Lucas's company, and he directed THX 1138.
- TIBCO Software – The Information Bus Company. The company was founded by Vivek Ranadive as Teknekron Software Systems in 1985.
- Tim Hortons – Canadian fast food doughnut, sandwich and coffee shop named after founder and hockey player Tim Horton. In Canada Tim Hortons is nicknamed "Tim's" and "Timmy's"; in America, the chain is nicknamed "Timmy Ho's".
- TNT N.V. and TNT Express – Thomas Nationwide Transport, an Australian company which was acquired by the Dutch postal company in 1996. The postal company renamed itself TNT N.V. in 2005. In 2011, TNT N.V. demerged; the express delivery company took the name TNT Express while the postal company renamed itself PostNL.
- Toshiba – named from the merger of consumer goods company Tokyo Denki (Tokyo Electric Co) and electrical firm Shibaura Seisaku-sho (Shibaura Engineering Works).
- Toyota – from the name of the founder, Sakichi Toyoda. Initially called Toyeda, it was changed after a contest for a better-sounding name. The new name was written in katakana with eight strokes, a number that is considered lucky in Japan.
- Triang – operating name for Lines Bros Ltd, which was founded by William, Walter and Arthur Edwin Lines. Three Lines make a triangle
- Tucows – an acronym for The Ultimate Collection Of Winsock Software.
- Tungsram – derived from Tungsten + Wolfram, two variations of the name of the main raw material of the lamp production.
- TVR – derived from the first name of the company founder TreVoR Wilkinson
- TWA – derived from Trans World Airlines. Before the airline opened up its first international route from New York to Paris in the 1950s, it was a domestic operation that focused on serving Los Angeles and San Francisco from New York, operating under the name Transcontinental and Western Air. Keeping the initials and rebranding as a global airline was a stroke of marketing continuity genius.
- Twinings – named after founder Thomas Twining, who set up a tea-shop on the Strand in London in 1706.
- Twitter – Having rejected the name Twitch for their social networking service, co-founder Jack Dorsey says: "we looked in the dictionary for words around it and we came across the word 'twitter' and it was just perfect. The definition was 'a short burst of inconsequential information', and 'chirps from birds'. And that's exactly what the product was."
Read more about this topic: List Of Company Name Etymologies