| 1 | GRE | Southeast European Airlines | IATA: 6J, Callsign: Seea Air, Ceased operations | GR | AVCODES |
| 2 | GRE | Greece Airways | Callsign: Greece Airways, | GR | AVCODES |
| 3 | GRE | Greenlandcopter A/S | | GRO | AVCODES |
| 4 | GRE | Air Scotland | | | ICAO1 |
| 5 | GREA | GREATLAND TRANSPORT INC | | | SCAC4 |
| 6 | GREA | Grand Rapids Eastern | Real: GR | USA | TRAFFIC |
| 7 | GREB | GREGG DRILLING AND TESTING INC | | | SCAC4 |
| 8 | GREC | GEORGETOWN RAIL EQUIPMENT CO | | | SCAC4 |
| 9 | GRED | GREGG TRUCKING | | | SCAC4 |
| 10 | GREI | GREEN ISLAND TRANSPORT LTD | | | SCAC4 |
| 11 | GREJ | GLOBAL RELOGISTICS INC | | | SCAC4 |
| 12 | GREL | GREEN MOTOR LINES INCORPORATED | | | SCAC4 |
| 13 | GREM | GREMILLION TRUCKING INC | | | SCAC4 |
| 14 | GREN | Société d'économie mixte des transports publics de l'agglomération grenobloise | Real: TAG, City: Grenoble | F | TRAFFIC |
| 15 | GREO | GFS TRANSPORTATION INC | | | SCAC4 |
| 16 | GREP | GREYHOUND EXPOSITION SERVICES, Las Vegas Convention Service Co | | | SCAC1 |
| 17 | GRER | Grenland Rail AS | Real: GRAS | N | TRAFFIC |
| 18 | GREU | M.A. GRENDI DAL 1828 S.P.A. | | I | BIC |
| 19 | GREU | Greuter AG | | CH | TRAFFIC |
| 20 | GREW | GREWAL BROS TRUCKING | | | SCAC4 |
| 21 | GREX | Georgetown Rail Equipment Co. | 1/1994 (not listed); added 7/1998; 7/2000-7/2005 | | NAKINA |
| 22 | GREX | Georgetown Rail Equipment Co. | 1/94; added 7/98; 7/2000 | | NRHS |
| 23 | GREX | GEORGETOWN RAIL EQUIPMENT COMPANY | | | PWRC |
| 24 | GREX | Georgetown Rail Equipment | | | RSRV |
| 25 | GREX | GEORGETOWN RAIL EQUIPMENT COMPANY | | | SCAC4 |
| 26 | GREY | GREYSTONE LOGISTICS | | | SCAC4 |
| 27 | GREYH | Greyhound | | USA | TRAFFIC |
