| GULFPOINTE II CONDOMINIUM ASSOCIATION, INC.Marathon, FL · Active | Marathon, FL | Nonprofit | Jan 29, 1988 | Active |
| WITH LOVE GIVEN, INC.Gulf Marathon, FL · Inactive | Gulf Marathon, FL | Nonprofit | Nov 6, 2025 | Inactive |
| MARATHON TERRACES INC.Marathon, FL · Active | Marathon, FL | Nonprofit | Sep 29, 2025 | Active |
| MARATHON NEW LIFE ASSEMBLY OF GOD, INC.Marathon, FL · Active | Marathon, FL | Nonprofit | Feb 26, 1988 | Active |
| PRO-FORM SPORTS, INC.Marathon, FL · Active | Marathon, FL | Nonprofit | Mar 5, 2026 | Active |
| HELPING HANDS COMMUNITY FOUNDATION, INCMarathon, FL · Active | Marathon, FL | Nonprofit | Mar 6, 2026 | Active |
| MINIFINS SOFTBALL INC.Marathon, FL · Active | Marathon, FL | Nonprofit | Apr 13, 2026 | Active |
| KEY WEST ISLAND CONCHS INCMarathon, FL · Active | Marathon, FL | Nonprofit | Apr 17, 2026 | Active |
| LOCAL 3909 THE PROFESSIONAL FIREFIGHTERS OF MONROE COUNTY IAFF CORPMarathon, FL · Active | Marathon, FL | Nonprofit | Apr 24, 2026 | Active |
| ANCIENT UNDERSEA EXPEDITION INC.Marathon, FL · Active | Marathon, FL | Nonprofit | May 20, 2026 | Active |
| LA CURA, INC.Marathon, FL · Active | Marathon, FL | Nonprofit | Jul 13, 2026 | Active |
| OCEANSIDE 73RD CONDOMINIUM ASSOCIATION, INC.Marathon, FL · Active | Marathon, FL | Nonprofit | Jul 14, 2026 | Active |
| ENGLISH FOR ALL CORPMarathon, FL · Active | Marathon, FL | Nonprofit | Jul 17, 2026 | Active |
| MARATHON JUNIOR FOOTBALL INC.Marathon, FL · Active | Marathon, FL | Nonprofit | Aug 12, 2026 | Active |
| WILD BLUE VETERANS PROJECT, INC.Marathon, FL · Active | Marathon, FL | Nonprofit | Aug 28, 2026 | Active |
| LEEWARD ACRES SOUTH AT LITTLE TORCH KEY PROPERTY OWNER'S ASSOCIATION, INC.Marathon, FL · Inactive | Marathon, FL | Nonprofit | Aug 29, 1988 | Inactive |
| DIVE INDUSTRY ASSOCIATION, INC.Marathon, FL · Inactive | Marathon, FL | Nonprofit | Jan 25, 1989 | Inactive |
| ONE HUNDRED CLUB OF MONROE COUNTY, INC.Marathon, FL · Active | Marathon, FL | Nonprofit | Feb 14, 1989 | Active |
| TINGLER/TREASURE CANAL MAINTENANCE ASSOCIATION INC.Marathon, FL · Inactive | Marathon, FL | Nonprofit | Apr 10, 1989 | Inactive |
| MONROE COUNTY FIRE CHIEFS' ASSOCIATION, INC.Marathon, FL · Inactive | Marathon, FL | Nonprofit | Apr 10, 1989 | Inactive |
| VACA KEY YACHTING ASSOCIATION, INC.Marathon, FL · Inactive | Marathon, FL | Nonprofit | Apr 24, 1989 | Inactive |
| FLORIDA KEYS FLYING CLUB, INC.Marathon, FL · Inactive | Marathon, FL | Nonprofit | Jun 27, 1989 | Inactive |
| HAWKS CAY COMMUNITY ASSOCIATION, INC.Duck Key, FL · Active | Duck Key, FL | Nonprofit | Aug 21, 1989 | Active |
| MARINA VILLAS AT HAWK'S CAY CONDOMINIUM ASSOCIATION, INC.Marathon, FL · Active | Marathon, FL | Nonprofit | Aug 22, 1989 | Active |
| GOLDEN LEAF ENTERPRISES, INC.Marathon, FL · Inactive | Marathon, FL | Nonprofit | Sep 6, 1989 | Inactive |
| FLORIDA KEYS AREA HEALTH EDUCATION CENTER, INC.Marathon, FL · Active | Marathon, FL | Nonprofit | Jan 25, 1990 | Active |
| OLDE TOWNE CENTRE CONDOMINIUM ASSOCIATION, INC.Marathon, FL · Active | Marathon, FL | Nonprofit | Mar 14, 1990 | Active |
| FISHERMEN'S HOSPITAL AUXILIARY, INC.Marathon, FL · Inactive | Marathon, FL | Nonprofit | Mar 12, 1990 | Inactive |
| MARATHON CHURCH OF CHRIST, INC.Marathon, FL · Active | Marathon, FL | Nonprofit | Mar 15, 1990 | Active |
| DUCK KEY WASTEWATER COOPERATIVE, INC.Duck Key, FL · Inactive | Duck Key, FL | Nonprofit | Apr 27, 1990 | Inactive |
| FLORIDA KEYS ART LEAGUE, INC.Marathon, FL · Inactive | Marathon, FL | Nonprofit | Apr 27, 1990 | Inactive |
| MARATHON INTERNATIONAL BONEFISH CLUB, INC.Marathon, FL · Active | Marathon, FL | Nonprofit | Jun 14, 1990 | Active |
| MONROE COUNTY COMMERCIAL FISHERMEN, INC.Marathon, FL · Active | Marathon, FL | Nonprofit | Aug 14, 1990 | Active |
| CALVARY BAPTIST CHURCH OF MARATHON, FLORIDA INC.Marathon, FL · Active | Marathon, FL | Nonprofit | Sep 13, 1990 | Active |
| MARATHON TRAILERAMA HOMEOWNERS INC.Marathon, FL · Inactive | Marathon, FL | Nonprofit | Oct 18, 1990 | Inactive |
| COCO PLUM TERRACES CONDOMINIUM ASSOCIATION, INC.Marathon, FL · Active | Marathon, FL | Nonprofit | Oct 26, 1990 | Active |
| HIDDEN HARBOR MARINE ENVIRONMENTAL PROJECT, INC.Marathon, FL · Active | Marathon, FL | Nonprofit | Jan 22, 1991 | Active |
| ZONTA CLUB OF MARATHON, INC.Marathon, FL · Inactive | Marathon, FL | Nonprofit | Feb 19, 1991 | Inactive |
| MARATHON MANOR RESIDENT FOUNDATION, INC.Marathon, FL · Inactive | Marathon, FL | Nonprofit | Jun 6, 1991 | Inactive |
| ISLAND AERO CLUB, INC.Marathon, FL · Inactive | Marathon, FL | Nonprofit | Jun 6, 1991 | Inactive |
| HABITAT FOR HUMANITY OF THE MIDDLE KEYS, INC.Marathon, FL · Active | Marathon, FL | Nonprofit | Aug 16, 1991 | Active |
| MARATHON GUIDES' ASSOCIATION, INC.Marathon, FL · Inactive | Marathon, FL | Nonprofit | Oct 17, 1991 | Inactive |
| INDEPENDENT TOWERS & SALVORS ASSOCIATION INC.Marathon, FL · Inactive | Marathon, FL | Nonprofit | Nov 1, 1991 | Inactive |
| EVANGELICAL GOSPEL ASSEMBLY, INC.Marathon, FL · Inactive | Marathon, FL | Nonprofit | May 26, 1992 | Inactive |
| SUNRISE ISLE HOMEOWNER'S ASSOCIATION, INC.Marathon, FL · Active | Marathon, FL | Nonprofit | May 28, 1992 | Active |
| ALLAMANDA GROUP, INC.Marathon, FL · Inactive | Marathon, FL | Nonprofit | Jun 10, 1992 | Inactive |
| UNITED STATES FELLOWSHIP OF FLORIDA, INC.Marathon, FL · Inactive | Marathon, FL | Nonprofit | Jun 23, 1992 | Inactive |
| FLORIDA KEYS RENAISSANCE FAIRE, INC.Marathon, FL · Inactive | Marathon, FL | Nonprofit | Sep 14, 1992 | Inactive |
| PIGEON KEY FOUNDATION, INC.Marathon, FL · Active | Marathon, FL | Nonprofit | Oct 7, 1992 | Active |
| FRATERNAL ORDER OF POLICE, MARATHON LODGE #73, INC.Marathon, FL · Inactive | Marathon, FL | Nonprofit | Nov 18, 1992 | Inactive |