Tei may refer to:

• Sandister Tei, Ghanaian journalist and Wikimedian
• Tei (singer) (born 1983), Korean pop singer
• Tei, Bucharest, a neighborhood in Bucharest, Romania
• Tellurium monoiodide, a chemical compound with the formula TeI
• Towa Tei, an artist, record producer and DJ (b. 1965)

TEI may refer to:

• Tarlac Electric
• Text Encoding Initiative, a consortium that develops standards for digital texts
• Technological Educational Institute, a type of tertiary education institute in Greece
• Terminal Endpoint Identifier (TEI), together with Service Access Point Identifier (SAPI) the unique identification of terminal equipment in the ISDN DSS1 standard
• Tertiary Education Institution in New Zealand
• Tezu Airport in India (IATA code)
• Total Economic Impact, a financial metric (see Application Portfolio Management)
• Trans Earth Injection, the procedure that a spacecraft performs to get back into the Earth's gravitational influence
• Triethylindium, a chemical compound
• Tusaş Engine Industries, a Turkish aircraft engine manufacturer