TNB may stand for:
- Tacoma Narrows Bridge, a bridge in Washington, USA
- TNB frame (Tangent–Normal–Binormal), a mathematical coordinate system
- Tenaga Nasional Berhad, an electricity company in Malaysia
- National Theatre Bucharest (Teatrul Naţional "Ion Luca Caragiale" Bucureşti)
- Thursday Night Baseball
- Tetrazolium Nitroblue
- The Nasty Boys, a professional wrestling tag team
- Trinitrobenzene, an explosive
- Tommy No Bobs, ex chairman that ran Cork City into the ground
TNb may stand for:
- Total Nitrogen bound, a sum parameter in water and wastewater analytics