| H. A. CASTRO & COMPANY, LIMITED | Private company limited by shares | Dissolved |
| DCS CASTRO LIMITED | Private company limited by shares | Live |
| CASTROL (CHINA) LIMITED | Private company limited by shares | Live |
| U.K. CASTROL CO., LIMITED | Private company limited by shares | Dissolved |
| Castron Limited | Private company limited by shares | Live |
| CASTRON (HK) CO., LIMITED | Private company limited by shares | Dissolved |
| CASTRON ELECTRONICS CO., LIMITED | Private company limited by shares | Live |
| CASTRONG LIMITED | Private company limited by shares | Dissolved |
| CASTROOM LIMITED | Private company limited by shares | Dissolved |