- City of Medina
- City of New Philadelphia
- City of North Olmsted
- City of North Royalton
- City of Olmsted Falls
- City of Parma
- City of Parma Heights
- City of Rocky River
- City of Sandusky
- City of Seven Hills
- City of Shaker Heights
- City of Solon
- City of South Euclid
- City of Toledo
- City of University Heights
- City of Warren
- City of Warrensville Heights
- City of Westlake
- City of Youngstown
- Clermont County OH CVB
- Clermount County, Permit Central
- Cleveland Airport - Fairfield Inn by Marriott, OH
- Cleveland Area Board of Realtors
- Cleveland Association of Assocatio Executives
- Cleveland Cavaliers-Lake Erie Monsters Operating Company
- Cleveland Clinic
- Cleveland Clinic Akron General
- Cleveland Clinic Health System
- Cleveland Museum of Art
- Cleveland Museum of Natural History
- Cleveland Postal Employees Credit Union
- Cleveland State University
- Clinical Computing, Inc.
- Clinton Memorial Hospital
- CMH Specialized Transportation, Inc.
- Collins Gordon Bostwick Architects
- Columbus College of Arts and Design
- Columbus Marriott Northwest, Dublin
- Columbus North - Fairfield Inn by Marriott
- Columbus Prescription Pharmacies, Inc.
- Community Action Commission of Fayette County
- Community Blood Center-Community Tissue
- Community Hospitals and Wellness Centers - Bryan
- Community Memorial Hospital
- Community Shares
- Community Tissue Services
- ConAgra Foods of Sidney, Ohio
- Copeland Oaks
- Coshocton County Hospital
- Countrywide Home Loans