| 1 | ZU | Helios Airways Ltd | ICAO: HCY, Callsign: Helios, Established on 23 September 1998. Commenced operations on 15 May 2000. Name changed to Ajet w.e.f. 14 March 2006. Helios Airways Ltd | CY | AVCODES |
| 2 | ZU | Helios Airways Ltd | ICAO: HCY, Callsign: Helios, IATA designator changed to ZU | CY | AVCODES |
| 3 | ZU | Arca Aerovias Colombianas Ltda. | ICAO: AKC, Callsign: Arca, Ceased operations. | CO | AVCODES |
| 4 | ZU | Sunair Aviation Ltd. | ICAO: SAV, Callsign: Sunair, IATA designator ZU recalled. | NZ | AVCODES |
| 5 | ZU | Ajet Aviation Ltd | ICAO: AJY, Callsign: Ayjet, Ceased operations on 06 November 2006. Name changed from Helios Airways Ltd w.e.f. 14 March 2006 | CY | AVCODES |
| 6 | ZU | Air Bashkortostan Ltd | ICAO: BBT, Callsign: Agydal, IATA Prefix: 894, Commenced operations on 10 April 2006. Closed down on 09 October 2013 by parent company VIM Avia. IATA designator changed from BQ* | RUS | AVCODES |
| 7 | ZU | Ethiopian Mozambique Airlines, Ltd | ICAO: EMZ, Callsign: Emoz, IATA Prefix: 971, | MOC | AVCODES |
| 8 | ZUCH | ZUCHOWICZ LUTHIER, DOMINIK | | | SCAC4 |
| 9 | ZUESA | ZUE S.A. | | PL | VKM |
| 10 | ZUG | Smart rail GmbH | | D | TRAFFIC |
| 11 | ZUKOM | Zakład Usług Komunalnych Komorniki | | PL | TRAFFIC |
| 12 | ZUNA | ZUNIGA CHAIRES, MARIA GUADALUPE | | | SCAC4 |
| 13 | ZUNC | ZUNIGA CISNEROS, RODRIGO | | | SCAC4 |
| 14 | ZUNI | ZUNIGA SPECIALIZED CARRIERS L C | | | SCAC4 |
| 15 | ZURI | ZURITAS TRUCKING | | | SCAC4 |
| 16 | ZUT | ZUT Wągrowiec Józef Kosiński | | PL | VKM |
| 17 | ZUZU | CARGOSTORE WORLDWIDE TRADING LIMITED | | GB | BIC |
| 18 | ZUZU | CARGOSTORE INTERNATIONAL LIMITED | | | SCAC4 |
