| 1 | ZR | Muk Air | ICAO: MUK, Callsign: Mukair, IATA Prefix: 796, Designator ZR recalled by IATA | DK | AVCODES |
| 2 | ZR | Aviacon Zitotrans Air Company JSC | ICAO: AZS, Callsign: Zitotrans, | RUS | AVCODES |
| 3 | ZR | Casair Aviation Services Ltd. | | GB | AVCODES |
| 4 | ZRBSZG | Zakład Remontowo-Budowlany Szalejów Górny | | PL | TRAFFIC |
| 5 | ZRCA | Z R CARRIER | | | SCAC4 |
| 6 | ZRCN | ZIRCON (USA) LOGISTICS LTD | | | SCAC4 |
| 7 | ZRCS | ZAVALZA ROMERO, CARLOS SERGIO | | | SCAC4 |
| 8 | ZREU | ZREMB CHOJNICE S.A. | | PL | BIC |
| 9 | ZRFS | ZUEHLKE, RICHARD F & SONS | | | SCAC4 |
| 10 | ZRKPN | Zakład Robót Komunikacyjnych – DOM w Poznaniu Sp. z o.o. | | PL | VKM |
| 11 | ZRNX | Erie City Energy Division, Zurn Industries, Inc. | added 1/1972; 1/1975-1/1980; eliminated 5/1983; 1/1994-7/2005 (not listed) | | NAKINA |
| 12 | ZRNX | Erie City Energy Division, Zurn Industries, Inc. | added 1/72; 1/75-1/80; eliminated 5/83; 1/94-7/2000 | | NRHS |
| 13 | ZRNX | ERIE CITY ENERGY DIV., ZURN INDUSTRIES INC | | | PWRC |
| 14 | ZRNX | Zurn Industries Erie City Energy Division | | | RSRV |
| 15 | ZRNX | ERIE CITY ENERGY DIVN-ZURN INDUSTRI | | | SCAC4 |
| 16 | ZRS | Republika Srpska Railways | | BIH | TRAFFIC |
| 17 | ZRS | Željeznice Republike Srpske | | BA | VKM |
| 18 | ZRSB | ZERON, RICK STABLE | | | SCAC4 |
