| 1 | XO | LTE International Airways S.A. | ICAO: LTE, Callsign: Fun Jet, Established on 29 April 1987. Commenced operations on 01 November 1987. Ceased operations on 17 October 2008. Name changed to Volar Airlines w.e.f. 24 May 2001. Name reverted back to LTE International Airways S.A. during 2005. | E | AVCODES |
| 2 | XO | China Xinjiang Airlines | ICAO: CXJ, Callsign: Xinjiang, Designator XO* recalled by IATA. Name changed from Zinjiang Airlines | PRC | AVCODES |
| 3 | XO | Xinjiang Airlines | ICAO: CXJ, Callsign: Xinjiang, Name changed to ChinaZinjiang Airlines | PRC | AVCODES |
| 4 | XO | South East Asian Airlines (Seair) International, Inc. | ICAO: SGD, Callsign: Air Blue, IATA Prefix: 397, | RP | AVCODES |
| 5 | XOJ | PCMT Aviation/Xoket, Inc. | Callsign: Xojet, Name changed to Xojet, Inc. | USA | AVCODES |
| 6 | XOJ | Xojet, Inc. | Callsign: Xojet, ICAO callsign changed to Exojet. Name changed from PCMT Aviation/Xoket, Inc. | USA | AVCODES |
| 7 | XOJ | Xojet, Inc. | Callsign: Exojet, Name changed to Xojet Aviation LLC. ICAO callsign changed from Xojet. Name changed from PCMT Aviation/Xoket, Inc. | USA | AVCODES |
| 8 | XOJ | Xojet Aviation LLC | Callsign: Exojet, Name changed from Xojet, Inc. ICAO callsign changed from Xojet. Name changed from PCMT Aviation/Xoket, Inc. | USA | AVCODES |
| 9 | XOLO | X ONE (X1) LOGISTICS | | | SCAC4 |
| 10 | XOMU | EXXONMOBIL CORPORATION | | USA | BIC |
| 11 | XOMX | Exxon Mobil Corp. | added 7/2000; 7/2000-7/2005 | | NAKINA |
| 12 | XOMX | Exxon Mobil Corp. | added 7/2000; 7/2000 | | NRHS |
| 13 | XOMX | EXXON-MOBIL CORPORATION | | | PWRC |
| 14 | XOMX | Exxon-Mobil Corporation | | | RSRV |
| 15 | XOMX | EXXON MOBIL CORPORATION | | | SCAC4 |
| 16 | XONE | XPRESS NETWORK SOLUTIONS (A DIVISIO | | | SCAC4 |
| 17 | XOOZ | FLEXI-VAN LEASING INC | | | SCAC4 |
| 18 | XOXU | BULK CONTAINER GROUP LLC | | USA | BIC |
