Obj or OBJ may refer to:
Entities
- Ottawa Business Journal, a weekly business publication in Ottawa, Ontario, Canada
People
- Odell Beckham Jr. (born 1992), American football player, nicknamed OBJ
- Olusegun Obasanjo (born 1937), 5th and 12th President of Nigeria, nicknamed OBJ
Software
- OBJ (programming language), a programming language family developed in 1976, including OBJ2 and OBJ3
- U+FFFC  OBJECT REPLACEMENT CHARACTER, a replacement character used in computing
Files
With the .obj file extension:
- Object file, an organized machine code file created by a compiler
- Relocatable Object Module Format, an Object file for Intel microprocessors
- COFF, the object file format on 32-bit and 64-bit Windows
- Wavefront .obj file, a 3D geometry definition file format