| Castle Communication Technologies | Ohio |
| Castle Creek Biosciences, Inc. | Pennsylvania |
| Castle Ink | New York |
| Castle Island Ventures | |
| Castle Rock Computing | California |
| Castle Ventures Corporation | New Jersey |
| Castled Data, Inc. | California |
| CastleVax, Inc. | |
| Castlight Health | California |
| Castor | New York |
| Castor Project | California |
| CastorDoc | New York |
| Castro Computer Services, Inc. | California |
| Casual, Inc. | |
| CAT 5 Cable Company | Arkansas |
| Cat Daddy Games, LLC | Washington |
| CAT Software Services | |
| CAT Squared | Arkansas |
| CAT Technology, Inc. | New Jersey |
| Cat&Tonic | |
| CataBoom, LLC | Texas |
| Catachem, Inc. | |
| Catalant Technologies, Inc. | |
| Catalent, Inc. | New Jersey |
| Catalina | |
| Catalina Broadband Solutions | California |
| Catalina Scientific | Arizona |
| Catalist Technology, LLC | Indiana |
| Catalog Technologies, Inc. | |
| Catalogic Software, Inc. | New Jersey |
| Catalyst Accelerator | Colorado |
| Catalyst Campus for Technology and Innovation | |
| Catalyst Clinical Research | North Carolina |
| Catalyst Communications Technologies, Inc. | Virginia |
| Catalyst Computer Services, Inc. | California |
| Catalyst Cooperative | Colorado |
| Catalyst Equipment Corporation | Texas |
| Catalyst Group Marketing | |
| Catalyst Health Tech | Colorado |
| Catalyst Investors | New York |
| Catalyst IT | Iowa |
| Catalyst Marketing Company | |
| Catalyst Marketing Innovations, LLC | |
| Catalyst Online, LLC | Massachusetts |
| Catalyst OrthoScience, Inc. | Florida |
| Catalyst Pharmaceuticals, Inc. | |
| Catalyst Software | |
| Catalyst Visuals, LLC | |
| Catalyst, Inc. | Indiana |
| Catalyst, LLC | North Dakota |