CTU
- CHH Txuri Urdin
- Can Tho University
- Capitol Technology University
- Caribbean Telecommunications Union
- Catholic Theological Union
- Cebu Technological University
- Chandigarh Transport Undertaking
- Chengdu Shuangliu International Airport
- Chicago Teachers Union
- Chienkuo Technology University
- Chunnam Techno University
- Clinical trials unit
- Coding tree unit
- Colorado Technical University
- Conservative Trade Unionists
- Corporate Training Unlimited
- Czech Technical University in Prague
- New Zealand Council of Trade Unions