- Cedar Park Regional Medical Center
- Cenetron Diagnostics
- Center for Neuromuscular Wellness
- Center Point Energy
- Centro de Salud Familiar La Fe
- Chantal Cookware Corp.
- Chase Payment Solutions
- ChaseCom LP
- Cherokee Staffing LLC
- Children's Health- Children's Medical Center
- Children's Memorial Hermann Hospital
- Chinese Community Center
- CHRISTUS Good Shepherd Emergency Center - Kilgore
- CHRISTUS Good Shepherd Medical Center Longview
- CHRISTUS Health System
- CHRISTUS Santa Rosa Alamo Heights
- CHRISTUS Santa Rosa City Centre
- CHRISTUS Santa Rosa Healthcare System
- CHRISTUS Santa Rosa New Braunfels
- CHRISTUS Santa Rosa San Marcos
- CHRISTUS Santa Rosa VNA Hospice
- CHRISTUS Santa Rosa Westover Hills
- CHRISTUS Santa Rose Medical Center
- CHRISTUS Transplant Institute
- Church on the Rock
- CIGNA HealthCare
- Cimarron
- City of Austin
- City of Fort Worth
- City of Houston Human Resources Department
- City of Parsons
- Clear Lake Area Chamber of Commerce
- Club Corp.
- Coastal Bank
- Cole Chemical and Distributing Inc.
- Collin County
- Comfort Inn Airport East, El Paso
- Comfort Inn Arlington South, Arlington
- Community Development Loan Fund
- Community Family Centers
- Community Resource Credit Union
- Complete Home Repair
- CompuCom
- Computize Inc.
- Concept Engineers Inc.
- Concho Valley Regional Food Bank
- Congregation Agudas Achim
- Conley Group
- Conoco
- Continental Airlines