| 501 | Longacre Oil & Gas | Enid, OK 73702 | Oil & Gas Operator | Mar 2013 |
| 502 | Lowery Roger | Duncan, OK 73534-0040 | Oil & Gas Operator | Sep 2012 |
| 503 | Lowry Exploration Inc | Tulsa, OK 74119 | Oil & Gas Operator | Nov 2025 |
| 504 | Lucky Oil Company | Comanche, OK 73529-0009 | Oil Operator | Dec 2025 |
| 505 | Luther Oil Inc | Cameron Park, CA 95682-8865 | Oil & Gas Operator | Apr 2020 |
| 506 | Lynan Energy Inc | Oklahoma City, OK 73120 | Oil & Gas Operator | May 2013 |
| 507 | M E Klein & Associates LLC | Washington, OK 73093-4663 | Oil & Gas Operator | Dec 2025 |
| 508 | M H Oil & Gas LLC | Okeene, OK 73763-0684 | Oil & Gas Operator | Feb 2013 |
| 509 | M-B Operating Co., Inc. | Rowlett, TX 75030 | Oil & Gas Operator | Feb 2026 |
| 510 | Mack Energy Co. | Duncan, OK 73534 | Oil & Gas Operator | Dec 2025 |
| 511 | Mack Oil Company | Duncan, OK 73534 | Oil & Gas Operator | Nov 2000 |
| 512 | Magellan Exploration Co LTD | Bethany, OK 73008-0909 | Oil & Gas Operator | Jun 2014 |
| 513 | Magma Resources LLC | Paoli, OK 73074 | Oil & Gas Operator | Apr 2025 |
| 514 | Maguire Oil Company | Dallas, TX 75270 | Oil & Gas Operator | Mar 2015 |
| 515 | Maier Resources Inc | Oklahoma City, OK 73157-2996 | Oil & Gas Operator | Mar 2015 |
| 516 | Majoil Company | Oklahoma City, OK 73112 | Oil & Gas Operator | Dec 1996 |
| 517 | Manuel Corporation | Wichita, KS 67206 | Oil & Gas Operator | Dec 2025 |
| 518 | Marathon Oil Company LLC | Houston, TX 77079 | Oil & Gas Operator | Dec 2025 |
| 519 | Mardale Drilling Company | Oklahoma City, OK 73157 | Oil Operator | Nov 1998 |
| 520 | Marlin Oil Corporation | Oklahoma City, OK 73113 | Oil & Gas Operator | Nov 2025 |
| 521 | Marlow Environmental LLC | Marlow, OK 73055 | Oil Operator | May 2022 |
| 522 | Marsh Oil & Gas Company | Oklahoma City, OK 73118 | Oil & Gas Operator | Nov 2025 |
| 523 | Marshall Oil Corporation | Oklahoma City, OK 73154 | Oil & Gas Operator | Apr 2017 |
| 524 | Mason Robert A | | Oil Operator | May 1993 |
| 525 | Mason Robert A Production Co | Edmond, OK 73013-9102 | Oil & Gas Operator | May 2013 |
| 526 | Masters Dorothy V | Davis, OK 73030-0397 | Oil & Gas Operator | May 2020 |
| 527 | Masters Loy C | Davis, OK 73030-0397 | Oil & Gas Operator | Apr 2005 |
| 528 | Maxland Oil Company | Haslet, TX 76052-5137 | Oil Operator | Nov 2014 |
| 529 | McCord J K | Duncan, OK 73534-0032 | Oil Operator | Mar 2009 |
| 530 | McGinley P A | Tulsa, OK 74101 | Oil & Gas Operator | Dec 1996 |
| 531 | McGoldrick Oil Company | Shreveport, LA 71129 | Oil & Gas Operator | Jul 2020 |
| 532 | McOr Oil & Gas Corp | Houston, TX 77002 | Oil & Gas Operator | Oct 2013 |
| 533 | Meadowbrook Oil Corporation Of Ok Inc | Del City, OK 73115-3608 | Oil & Gas Operator | Dec 2025 |
| 534 | Mel Cox Transports Inc | Comanche, OK 73529-7640 | Oil & Gas Operator | Jul 2022 |
| 535 | Mercer Pet Management Inc | Edmond, OK 73013-6677 | Oil & Gas Operator | Jan 2011 |
| 536 | Merit Energy Company | Dallas, TX 75240 | Oil & Gas Operator | Feb 2026 |
| 537 | Mesa Operating LP | Irving, TX 75039-3746 | Oil & Gas Operator | Oct 2010 |
| 538 | Mewbourne Oil Company | Tyler, TX 75711 | Oil & Gas Operator | Feb 2026 |
| 539 | MGF Oil Corporation | Tulsa, OK 74121 | Oil & Gas Operator | Jun 1998 |
| 540 | Mid Center Oil Company | | Oil & Gas Operator | Mar 2014 |
| 541 | Midstate Oil & Gas Company | Shawnee, OK 74801 | Oil & Gas Operator | Nov 2025 |
| 542 | Mija LLC | Oklahoma City, OK 73151 | Oil & Gas Operator | Dec 2025 |
| 543 | Milburn R Kenneth | Ardmore, OK 73402-1118 | Oil & Gas Operator | Sep 2014 |
| 544 | Mild Oil Company | Duncan, OK 73533-9532 | Oil Operator | Mar 2000 |
| 545 | Minor Jr W T | Wichita Falls, TX 76307 | Oil Operator | Nov 1998 |
| 546 | Mobil Exp & Prod Us Inc | Houston, TX 77060-1991 | Oil & Gas Operator | May 2001 |
| 547 | Mogo Operating, LLC | Norman, OK 73069 | Oil & Gas Operator | Nov 2025 |
| 548 | Mohawk Operating LLC | Oklahoma City, OK 73173-8907 | Gas Operator | Feb 2004 |
| 549 | Moore & Moore Energy Inc | Purcell, OK 73080-0674 | Oil & Gas Operator | Dec 2012 |
| 550 | Moore David K | Duncan, OK 73575 | Oil & Gas Operator | Oct 2009 |
| 551 | Mowdy Robert F | Coalgate, OK 74538 | Oil & Gas Operator | May 2001 |
| 552 | MSB Operating Company | Enid, OK 73703 | Oil & Gas Operator | Jan 2005 |
| 553 | MT Dora Energy Corporation | Duncan, OK 73533-1829 | Oil & Gas Operator | Apr 2014 |
| 554 | MT Dora Energy LLC | Houston, OK 77056-1940 | Oil & Gas Operator | Jun 2019 |
| 555 | MT Energy LLC | Waskom, TX 75692 | Oil & Gas Operator | Feb 2026 |
| 556 | Mustang Fuel Corp. Of Oklahoma | Oklahoma City, OK 73106 | Oil & Gas Operator | Nov 2016 |
| 557 | Mustang Fuel Corporation | Oklahoma City, OK 73114 | Oil & Gas Operator | Dec 2025 |
| 558 | Mustang Gas Products LLC | Oklahoma City, OK 73114-7406 | Oil & Gas Operator | Sep 2022 |
| 559 | MW Petroleum Corporation | Houston, TX 77056 | Oil & Gas Operator | Mar 2015 |
| 560 | Myjo Oil Corporation | Breckenridge, TX 76024 | Oil Operator | Jul 1996 |
| 561 | N & N Oil LLC | Duncan, OK 73533 | Oil & Gas Operator | May 2023 |
| 562 | Naro Oil Corporation | Dallas, TX 75230-1986 | Oil & Gas Operator | Nov 2003 |
| 563 | Natural Gas Pipeline Co Of Am LLC | Downers Grove, IL 60515-3708 | Oil & Gas Operator | Mar 2015 |
| 564 | Nbi Services, Inc. | Tulsa, OK 74159 | Oil & Gas Operator | Feb 2026 |
| 565 | Nelco Oil & Gas | Duncan, OK 73533-1516 | Oil & Gas Operator | Oct 2015 |
| 566 | Newpek, LLC | Irving, TX 75039 | Oil & Gas Operator | Sep 2016 |
| 567 | Nichols, Irl. A. Trust B | Duncan, OK 73534 | Oil & Gas Operator | Sep 2000 |
| 568 | Nitro Petroleum Inc | Phoenix, AZ 85016-4599 | Oil & Gas Operator | May 2020 |
| 569 | Noble Energy Inc | Midland, TX 79706 | Oil & Gas Operator | Feb 2026 |
| 570 | Noble Energy Production Inc | Houston, TX 77067 | Oil & Gas Operator | Feb 2026 |
| 571 | Nooner Cynthia | Ratliff City, OK 73481 | Oil Operator | Oct 2025 |
| 572 | Nordstrand Engineering Inc | Houston, TX 77019 | Oil & Gas Operator | Feb 2026 |
| 573 | North American Energy Inc | Duncan, OK 73533-9604 | Oil & Gas Operator | Nov 2000 |
| 574 | Northbrook Oil & Gas Co LLC | Norman, OK 73072 | Oil & Gas Operator | Nov 2014 |
| 575 | Northbrook Oil & Gas Company | Norman, OK 73070-4916 | Oil & Gas Operator | Jun 2016 |
| 576 | Nossaman E Oil Inc | Del City, OK 73155-5449 | Oil Operator | Oct 2002 |
| 577 | Nub'S Well Servicing Inc | Ratliff City, OK 73481 | Oil & Gas Operator | Dec 2025 |
| 578 | Nutt Jerrie | Duncan, OK 73534-0698 | Oil & Gas Operator | Nov 2016 |
| 579 | O'Neal Oil & Gas Co | Fort Worth, TX 76107-1479 | Oil & Gas Operator | Dec 2025 |
| 580 | O'Neal Oil Company | Nocona, TX 76255 | Oil & Gas Operator | Feb 2026 |
| 581 | O'Neal, Lindell | Nocona, TX 76255 | Oil & Gas Operator | Nov 2025 |
| 582 | Oil Producers, Inc. Of Kansas | Wichita, KS 67206 | Oil & Gas Operator | Feb 2026 |
| 583 | Oilbank Production LLC | Norman, OK 73072 | Oil Operator | Nov 2025 |
| 584 | Oilco Energy Inc | Duncan, OK 73533 | Oil & Gas Operator | Mar 2015 |
| 585 | Oilwell Operators, Inc. | Pampa, TX 79066 | Oil & Gas Operator | Feb 2026 |
| 586 | Oklahoma O & G Royalties Inc | Duncan, OK 73533 | Oil & Gas Operator | Nov 2000 |
| 587 | Oklahoma Oil & Gas MGMT Inc | Edmond, OK 73083-6786 | Oil & Gas Operator | Nov 2025 |
| 588 | Oklahoma Prime Energy LLC | Ardmore, OK 73401 | Oil Operator | May 2020 |
| 589 | Oklahoma Tank Service Inc | Oklahoma City, OK 73143 | Oil Operator | Aug 1997 |
| 590 | Okmar Oil Company | Marietta, OH 45750 | Oil & Gas Operator | Jun 2005 |
| 591 | Oktex Operating LLC | Edmond, OK 73013-1961 | Oil & Gas Operator | May 2020 |
| 592 | Old Dominion Oil Corporation | Oklahoma City, OK 73107 | Oil & Gas Operator | Apr 2009 |
| 593 | Oneok Exploration Company | Tulsa, OK 74102 | Oil & Gas Operator | Feb 2017 |
| 594 | Oneok Field Services Company | Tulsa, OK 74103 | Oil & Gas Operator | Jul 2022 |
| 595 | Oneok Gas Transportation Co | Tulsa, OK 74121-2089 | Oil & Gas Operator | Oct 2014 |
| 596 | Oneok Resources Company | Tulsa, OK 74102 | Oil & Gas Operator | Feb 2017 |
| 597 | Otc/Occ Not Assigned | | Oil & Gas Operator | Dec 2024 |
| 598 | Ovintiv Mid-Continent Inc. | The Woodlands, TX 77380-2764 | Oil & Gas Operator | Dec 2025 |
| 599 | Ovintiv USA Inc. | Denver, CO 80202 | Oil & Gas Operator | Feb 2026 |
| 600 | Oxy USA Inc | Houston, TX 77046 | Oil & Gas Operator | Feb 2026 |