| MARTHA AND BETTY FOUNDATION, INC.Marathon, FL · Inactive | Marathon, FL | Nonprofit | Dec 7, 2007 | Inactive |
| COCOPLUM BEACH AND TENNIS CLUB CONDOMINIUM ASSOCIATION, INC.Marathon, FL · Active | Marathon, FL | Nonprofit | Jan 31, 1985 | Active |
| UNICORN THEATRE, INC.Marathon, FL · Inactive | Marathon, FL | Nonprofit | Feb 19, 1985 | Inactive |
| GULFSIDE VILLAGE CONDOMINIUM ASSOCIATION, INC.Marathon, FL · Active | Marathon, FL | Nonprofit | Mar 5, 1985 | Active |
| GRASSY KEY ASSOCIATION, INC.Marathon, FL · Inactive | Marathon, FL | Nonprofit | Jan 2, 2008 | Inactive |
| NAMI-MIDDLE KEYS, INC.Marathon, FL · Inactive | Marathon, FL | Nonprofit | Jan 22, 2008 | Inactive |
| N20050, INC.Marathon, FL · Inactive | Marathon, FL | Nonprofit | Feb 6, 2008 | Inactive |
| N7689U, INC.Marathon, FL · Inactive | Marathon, FL | Nonprofit | Feb 6, 2008 | Inactive |
| N220WB, INC.Marathon, FL · Inactive | Marathon, FL | Nonprofit | Feb 6, 2008 | Inactive |
| GULFSTREAM VILLAGE AND SEACREST HEIGHTS NEIGHBORHOOD ASSOCIATION, INC.Marathon, FL · Inactive | Marathon, FL | Nonprofit | Apr 25, 2008 | Inactive |
| MARATHON FLORIDA FLYING CLUB, INCMarathon, FL · Inactive | Marathon, FL | Nonprofit | Jul 9, 2008 | Inactive |
| FLORIDA KEYS CHAPTER OF THE ICC & BOAF, INC.Marathon, FL · Inactive | Marathon, FL | Nonprofit | Jul 18, 2008 | Inactive |
| LADIES' AUXILIARY MARATHON POWER SQUADRON, INC.Marathon, FL · Inactive | Marathon, FL | Nonprofit | Apr 4, 1985 | Inactive |
| LIBERTY LIGHTHOUSE OUTREACH MINISTRIES, INC.Marathon, FL · Inactive | Marathon, FL | Nonprofit | Apr 11, 1985 | Inactive |
| COCO PLUM BEACH VILLAS CONDOMINIUM ASSOCIATION, INC.Marathon, FL · Active | Marathon, FL | Nonprofit | Apr 17, 1985 | Active |
| AYITI HISTORY & RESOURCES, INCMiami Garden, FL · Inactive | Miami Garden, FL | Nonprofit | Oct 9, 2009 | Inactive |
| CARLSON GOSS FOUNDATION INCMarathon, FL · Inactive | Marathon, FL | Nonprofit | Nov 10, 2009 | Inactive |
| KNIGHT'S KEY VILLAGE CONDOMINIUM ASSOCIATION, INC.Marathon, FL · Inactive | Marathon, FL | Nonprofit | May 23, 1985 | Inactive |
| GOD'S ARMY MINISTRY CORPMarathon, FL · Inactive | Marathon, FL | Nonprofit | Feb 11, 2010 | Inactive |
| CLEANUP THE KEYS, INC.Marathon, FL · Inactive | Marathon, FL | Nonprofit | Apr 15, 2010 | Inactive |
| HABITAT HAMMOCKS HOMEOWNERS' ASSOCIATION, INC.Marathon, FL · Inactive | Marathon, FL | Nonprofit | Jun 11, 2010 | Inactive |
| SAFE HARBOR ANIMAL RESCUE OF THE KEYS INCORPORATEDMarathon, FL · Inactive | Marathon, FL | Nonprofit | Jul 19, 2010 | Inactive |
| IGLESIA DE DIOS DE MARATHON, INC.Marathon, FL · Inactive | Marathon, FL | Nonprofit | Aug 3, 2010 | Inactive |
| VETERANS COUNCIL OF MONROE COUNTY INC.Marathon, FL · Inactive | Marathon, FL | Nonprofit | Sep 15, 2010 | Inactive |
| THE MORE THAN WORDS FOUNDATION, INC.Marathon, FL · Inactive | Marathon, FL | Nonprofit | Oct 18, 2010 | Inactive |
| SOUTH FLORIDA GERMAN-AMERICAN FRIENDSHIP ASSOCIATION, INC.Marathon, FL · Inactive | Marathon, FL | Nonprofit | Jul 30, 1985 | Inactive |
| GREATER MARATHON HOTEL-MOTEL ASSOCIATION, INC.Marathon, FL · Inactive | Marathon, FL | Nonprofit | Aug 12, 1985 | Inactive |
| FISHERMEN'S HOSPITAL FOUNDATION, INC.Marathon, FL · Inactive | Marathon, FL | Nonprofit | Apr 20, 2011 | Inactive |
| FRIENDS OF OLD SEVEN, INC.Marathon, FL · Inactive | Marathon, FL | Nonprofit | Jul 18, 2011 | Inactive |
| MARATRI INC.Marathon, FL · Inactive | Marathon, FL | Nonprofit | Aug 24, 2011 | Inactive |
| MARATHON LANDING AND FLYING CLUB, INC.Marathon, FL · Active | Marathon, FL | Nonprofit | Aug 30, 2011 | Active |
| MARATHON LANDINGS CLUB INC.Marathon, FL · Inactive | Marathon, FL | Nonprofit | Oct 4, 2011 | Inactive |
| GRACE JONES COMMUNITY CENTER, INC.Marathon, FL · Active | Marathon, FL | Nonprofit | Oct 18, 1985 | Active |
| SEEK AND AID INC.Carol City, FL · Inactive | Carol City, FL | Nonprofit | Oct 21, 1985 | Inactive |
| SNIP, INC.Marathon, FL · Inactive | Marathon, FL | Nonprofit | Jan 20, 2012 | Inactive |
| FRIENDS OF THE MARATHON AIRPORT, INC.Marathon, FL · Inactive | Marathon, FL | Nonprofit | Jan 30, 2012 | Inactive |
| PARADISE 33040 INCMarathon, FL · Inactive | Marathon, FL | Nonprofit | Aug 2, 2012 | Inactive |
| HONEY LAKE CHURCH & WORLDWIDE MINISTRIES, INC.Duck Key, FL · Inactive | Duck Key, FL | Nonprofit | Jan 4, 2013 | Inactive |
| MARATHON TARPON TOURNAMENTS INC.Marathon, FL · Inactive | Marathon, FL | Nonprofit | Apr 5, 2013 | Inactive |
| MASTERS AND WARDENS OF DISTRICT 36 INCMarathon, FL · Inactive | Marathon, FL | Nonprofit | May 16, 2013 | Inactive |
| MARATHON COMMUNITY OUTREACH, INC.Marathon, FL · Inactive | Marathon, FL | Nonprofit | Jul 26, 2013 | Inactive |
| COMMUNITY LEARNING MINISTRIES INCMarathon, FL · Inactive | Marathon, FL | Nonprofit | Jan 2, 2014 | Inactive |
| FLORIDA KEYS SUSTAINABLE GARDENS INC.Marathon, FL · Inactive | Marathon, FL | Nonprofit | Jan 29, 2014 | Inactive |
| KEYS COMMUNITY GARDENS INCORPORATEDMarathon, FL · Inactive | Marathon, FL | Nonprofit | Apr 15, 2014 | Inactive |
| MARATHON LIONS CLUB, INC.Marathon, FL · Inactive | Marathon, FL | Nonprofit | Jul 31, 2014 | Inactive |
| DISABLED AMERICAN VETERANS AUXILIARY UNIT 122, INC.Marathon, FL · Inactive | Marathon, FL | Nonprofit | Oct 1, 2014 | Inactive |
| SAVE SOMBRERO BEACH ROAD, INC.Marathon, FL · Inactive | Marathon, FL | Nonprofit | Dec 18, 2014 | Inactive |
| MARATHON BAND PARENTS' COMMITTEE, INC.Marathon, FL · Inactive | Marathon, FL | Nonprofit | Apr 2, 1986 | Inactive |
| REAL ESTATE ACTION COUNCIL OF MONROE, INC.Marathon, FL · Inactive | Marathon, FL | Nonprofit | Apr 9, 1986 | Inactive |
| SIMPLE CHURCH, INC.Marathon, FL · Inactive | Marathon, FL | Nonprofit | Jan 6, 2015 | Inactive |