| CLARK COUNTY 4-H COMMITTEE, INC. | — | 631028 | 1984-03-23 | Canceled | SPRINGFIELD |
| CLARK COUNTY ADJUSTMENT SERVICE, INC. | — | 299427 | 1961-04-05 | Canceled | SPRINGFIELD |
| CLARK COUNTY AGRICULTURAL SOCIETY | Arts and entertainment | 137988 | 1929-08-19 | Active | SPRINGFIELD |
| CLARK COUNTY AMATEUR RADIO ASSOCIATION, INCORPORATED | — | 550258 | 1980-02-19 | Active | SPRINGFIELD |
| CLARK COUNTY AMVETS POST #37 | — | 842352 | 1993-04-05 | Active | SPRINGFIELD |
| CLARK COUNTY AMVETS, POST NO. 37 | — | 473264 | 1975-10-31 | Dissolved | SPRINGFIELD |
| CLARK COUNTY ASSOCIATION OF FUTURE FARMERS | — | 290162 | 1960-04-22 | Canceled | SPRINGFIELD |
| CLARK COUNTY AUTO WRECKERS, INC. | — | 335236 | 1964-11-19 | Canceled | SPRINGFIELD |
| CLARK COUNTY BLOOD ASSURANCE ASSOCIATION | — | 261009 | 1957-01-30 | Canceled | SPRINGFIELD |
| CLARK COUNTY BOWLING PROPRIETORS ASSOCIATION | — | 313870 | 1962-09-17 | Canceled | SPRINGFIELD |
| CLARK COUNTY C.B. CLUB INC. | — | 750822 | 1989-06-02 | Canceled | SPRINGFIELD |
| CLARK COUNTY CAR CO., INC. | — | 508639 | 1977-12-16 | Canceled | SPRINGFIELD |
| CLARK COUNTY CHAPTER #291 OF AARP, INC. | — | 352113 | 1966-06-24 | Canceled | SPRINGFIELD |
| CLARK COUNTY CHAPTER NO. 13 DISABLED AMERICAN VETERANS | — | 190566 | 1945-08-30 | Pending | SPRINGFIELD |
| CLARK COUNTY CITIZENS BAND RADIO CLUB | — | 401120 | 1970-08-21 | Canceled | SPRINGFIELD |
| CLARK COUNTY CIVILIAN RANGER PATROL | — | 4824178 | 2022-02-24 | Active | SPRINGFIELD |
| CLARK COUNTY COMMAND OFFICERS ASSOCIATION INC. | — | 618110 | 1983-08-08 | Canceled | SPRINGFIELD |
| CLARK COUNTY COMMUNITY ACTION CORPORATION | — | 339572 | 1965-04-19 | Canceled | SPRINGFIELD |
| CLARK COUNTY CONTRACT COMPANY | — | 265442 | 1957-08-10 | Canceled | SPRINGFIELD |
| CLARK COUNTY COON HUNTERS, INC. | — | 340327 | 1965-05-14 | Active | SPRINGFIELD |
| CLARK COUNTY COUNCIL OF CHURCHES | — | 276473 | 1958-12-27 | Canceled | SPRINGFIELD |
| CLARK COUNTY COUNCIL OF THE BLIND, INC. | — | 536705 | 1979-06-06 | Canceled | SPRINGFIELD |
| CLARK COUNTY DAIRY ASSOCIATION, INC. | — | 195662 | 1946-06-14 | Canceled | SPRINGFIELD |
| CLARK COUNTY DEPUTIES ASSOCIATION | — | 541437 | 1979-09-04 | Canceled | SPRINGFIELD |
| CLARK COUNTY DEPUTIES FRATERNAL ORDER OF POLICE LODGE 209 | — | 2309042 | 2014-07-07 | Active | SPRINGFIELD |
| CLARK COUNTY DEVELOPMENT CORPORATION | — | 597180 | 1982-07-06 | Canceled | SPRINGFIELD |
| CLARK COUNTY DISTRIBUTORS,INC. | — | 204583 | 1947-10-18 | Canceled | SPRINGFIELD |
| CLARK COUNTY DIVISION, OHIO INFORMATION COMMITTEE, INC. | — | 250081 | 1955-09-29 | Canceled | SPRINGFIELD |
| CLARK COUNTY DOG OWNERS CLUB | — | 335832 | 1964-12-15 | Dissolved | SPRINGFIELD |
| CLARK COUNTY EASTER SEAL SOCIETY, INC. | — | 560294 | 1980-09-02 | Dissolved | SPRINGFIELD |
| CLARK COUNTY EMPLOYEES CREDIT UNION, INC. | — | 283143 | 1959-08-08 | Dissolved | SPRINGFIELD |
| CLARK COUNTY EXPRESS TRACK CLUB | — | 583435 | 1981-10-13 | Canceled | SPRINGFIELD |
| CLARK COUNTY FARM BUREAU, INC. | — | 202014 | 1947-05-19 | Active | SPRINGFIELD |
| CLARK COUNTY FIRE CHIEF'S ASSOCIATION | — | 652184 | 1985-03-29 | Canceled | SPRINGFIELD |
| CLARK COUNTY FULLER CENTER FOR HOUSING | — | 763614 | 1989-12-28 | Dissolved | SPRINGFIELD |
| CLARK COUNTY GENERAL CONTRACTORS CONSTRUCTION CORPORATION | — | 687537 | 1986-10-23 | Canceled | SPRINGFIELD |
| CLARK COUNTY GLASS COMPANY | — | 377882 | 1968-11-26 | Active | SPRINGFIELD |
| CLARK COUNTY GLASS COMPANY | — | 129690 | 1928-02-07 | Dissolved | SPRINGFIELD |
| CLARK COUNTY HARNESS HORSEMEN'S ASSOCIATION | — | 628504 | 1984-02-09 | Canceled | SPRINGFIELD |
| CLARK COUNTY HOME BUILDERS ASSOCIATION | — | 300329 | 1961-05-06 | Canceled | SPRINGFIELD |
| CLARK COUNTY HOSPITAL AUTHORITY | — | 349952 | 1966-04-11 | Dissolved | SPRINGFIELD |
| CLARK COUNTY INVESTMENTS, INC. | — | 768784 | 1990-03-15 | Canceled | SPRINGFIELD |
| CLARK COUNTY JAIL CHAPLAINCY PROGRAM, INC. | — | 606857 | 1983-01-07 | Active | SPRINGFIELD |
| CLARK COUNTY LABOR-MANAGEMENT COUNCIL | — | 670795 | 1986-02-07 | Canceled | SPRINGFIELD |
| CLARK COUNTY LAND REUTILIZATION CORPORATION | — | 2295058 | 2014-05-13 | Active | SPRINGFIELD |
| CLARK COUNTY LAW LIBRARY ASSOCIATION | — | 881074 | 1994-09-19 | Dissolved | SPRINGFIELD |
| CLARK COUNTY LEGAL SUPPORT PROFESSIONALS | — | 1029936 | 1998-08-21 | Canceled | SPRINGFIELD |
| CLARK COUNTY LITERACY COALITION | — | 741943 | 1989-01-30 | Active | SPRINGFIELD |
| CLARK COUNTY LIVE STOCK PROTECTION SOCIETY | — | 4797 | 1900-01-01 | Dissolved | SPRINGFIELD |
| CLARK COUNTY LOCAL FOODS COUNCIL | — | 4687905 | 2021-06-01 | Active | SPRINGFIELD |