- City of Stockholm, Sweden
- Claire Holloway
- Claire Kenyon
- Clare Snyder
- Claremont Colleges Student Chapter
- Clarence Lee
- Clark Cheng
- Clarke Rowan
- Claudia Perlich
- Claudio Caremi
- Claudio Lucarelli
- Claudio Wolter
- Clayton J. Thomas
- Clayton Tino
- Clemson University Student Chapter
- Cleveland, Ohio Case Study
- Clint Moore
- Clóvis C. Gonzaga
- Coca-Cola Enterprises
- Col William K. Klimack
