| 501 | Markan Oil Incor | | Oil Operator | Mar 1991 |
| 502 | Markay Oil & Gas Company | Midland, TX 79701 | Oil & Gas Operator | Sep 1998 |
| 503 | Marker Oil Compa | | Oil Operator | Jul 1985 |
| 504 | Market Street Energy, Inc. | Flatonia, TX 78941 | Oil & Gas Operator | Dec 2025 |
| 505 | Markham Enterprises Inc | | Oil & Gas Operator | May 1981 |
| 506 | Markham, Charles A., Jr. & Janet E. | Gowanda, NY 14070 | Gas Operator | Dec 2024 |
| 507 | Markley Exploration | Bixby, OK 74008-5332 | Oil & Gas Operator | Jan 2014 |
| 508 | Markley L C Corporation | Fletcher, OK 73541 | Oil & Gas Operator | Aug 2002 |
| 509 | Marks & Co., Inc. | | Oil & Gas Operator | Dec 2021 |
| 510 | Marks And Garner Production LTD Co | Hobbs, NM 88241 | Oil & Gas Operator | Sep 2010 |
| 511 | Marks Operating LLC | | Oil & Gas Operator | Jul 2016 |
| 512 | Marksmen Energy USA Inc | Worthington, OH 43085-1270 | Oil Operator | Dec 2023 |
| 513 | Markus Production | Littleton, CO 80123 | Oil & Gas Operator | Nov 2025 |
| 514 | Markus Production, Inc | | Oil & Gas Operator | Mar 2021 |
| 515 | Markwest Resources Inc | Englewood, CO 801125004 | Oil & Gas Operator | Jun 2003 |
| 516 | Marlan Anderson | | Oil Operator | Jan 2025 |
| 517 | Marler Philip | Purcell, OK 73080-1522 | Oil & Gas Operator | Nov 2016 |
| 518 | Marlin And Davis | | Oil Operator | Sep 1987 |
| 519 | Marlin Coastal, L.L.C. | | Oil & Gas Operator | Apr 2008 |
| 520 | Marlin Energy Offshore, L.L.C. | | Oil & Gas Operator | Jun 2006 |
| 521 | Marlin Energy Resources, LLC | Lafayette, LA 70503 | Oil & Gas Operator | May 2018 |
| 522 | Marlin Energy Southwest GP, LLC | Lafayette, LA 70503 | Oil & Gas Operator | Dec 2025 |
| 523 | Marlin Expl.,Inc&Exchg O&G Co | | Oil & Gas Operator | Jun 1987 |
| 524 | Marlin Exploration, Inc. | | Oil & Gas Operator | Oct 2006 |
| 525 | Marlin Exploration, LLC | | Oil & Gas Operator | Oct 2025 |
| 526 | Marlin Oil Company LLC | Gillette, WY 82718 | Oil & Gas Operator | Mar 2023 |
| 527 | Marlin Oil Corporation | Oklahoma City, OK 73113 | Oil & Gas Operator | Oct 2025 |
| 528 | Marlin Operating, LLC | Southlake, TX 76092 | Oil & Gas Operator | Nov 2025 |
| 529 | Marlin Pacific Oil & Gas | | Oil & Gas Operator | Dec 2003 |
| 530 | Marlin Resources, L.L.C. | Midland, TX 79702 | Oil & Gas Operator | Jan 2025 |
| 531 | Marlin, Bruce W | | Oil Operator | Oct 2025 |
| 532 | Marline Oil Corp | Houston, TX 77002 | Oil & Gas Operator | Dec 1989 |
| 533 | Marline Petroleum Corporation | | Oil & Gas Operator | Dec 1985 |
| 534 | Marlow Environmental LLC | Marlow, OK 73055 | Oil Operator | May 2022 |
| 535 | Marlyn Company | | Oil & Gas Operator | Dec 2009 |
| 536 | Marmac Petroleum | | Oil & Gas Operator | Oct 1994 |
| 537 | Marmac Petroleum Company | Denver, CO 80222 | Oil Operator | Apr 1998 |
| 538 | Marmac Resources Company | | Oil & Gas Operator | Mar 2015 |
| 539 | Marmac Resources Inc | | Oil Operator | Nov 1998 |
| 540 | Marmaton Oil Company | Houston, TX 77002 | Oil & Gas Operator | Jul 1998 |
| 541 | Marmik Oil Compa | | Oil Operator | Jun 1995 |
| 542 | Marmik Oil Company | El Dorado, AR 71730 | Oil & Gas Operator | Jan 2015 |
| 543 | Maroon Energy LLC | Spring, TX 77379 | Oil & Gas Operator | Feb 2025 |
| 544 | Maroski, Inc. | | Oil Operator | Jan 1989 |
| 545 | Marple Petroleum LLC | Edmond, OK 73013 | Oil Operator | Nov 2025 |
| 546 | Marquee Corporation | Houston, TX 77024 | Oil & Gas Operator | Dec 2025 |
| 547 | Marquis Resources, LLC | | Oil & Gas Operator | Jul 2021 |
| 548 | Marquis-Allred Eng Inc | | Oil & Gas Operator | Apr 1992 |
| 549 | Marquise Oil Properties Inc | Konawa, OK 74849 | Oil & Gas Operator | Nov 1992 |
| 550 | Marr Company | | Oil & Gas Operator | Mar 1989 |
| 551 | Marr, M. H. | Dallas, TX 75201 | Gas Operator | Jan 2002 |
| 552 | Marrakesh Oil Company | Oklahoma City, OK 73118 | Oil & Gas Operator | Jun 1995 |
| 553 | Marrow, N. S. | Austin, TX 78703 | Oil & Gas Operator | Aug 2012 |
| 554 | Marrs Bros Oil Co Inc | Drumright, OK 74030 | Oil Operator | Sep 1994 |
| 555 | Marrs, Richard L.(Deceased) | Arkansas City, KS 67005 | Oil & Gas Operator | Feb 2013 |
| 556 | Marsh Engineering, Inc. | | Oil & Gas Operator | Dec 1990 |
| 557 | Marsh Lonnie C | Konawa, OK 74849 | Oil & Gas Operator | Sep 2025 |
| 558 | Marsh Oil & Gas Company | Oklahoma City, OK 73118 | Oil & Gas Operator | Oct 2025 |
| 559 | Marsh Oil & Gas Field Services, Inc | Sebree, KY 42455 | Oil & Gas Operator | Dec 2023 |
| 560 | Marsh Operating Company | Dallas, TX 75221 | Oil & Gas Operator | Sep 2025 |
| 561 | Marsha Azar | | Oil & Gas Operator | Jan 2017 |
| 562 | Marshall & McCain | | Oil & Gas Operator | Oct 1988 |
| 563 | Marshall & Winston, Inc. | Midland, TX 79710 | Oil & Gas Operator | Nov 2025 |
| 564 | Marshall Energy, Inc. | Dallas, TX 75243 | Oil & Gas Operator | May 1997 |
| 565 | Marshall Exploration, Inc. | | Oil & Gas Operator | Jun 1992 |
| 566 | Marshall Lew L O | | Oil Operator | Jun 1994 |
| 567 | Marshall Oil Corporation | Oklahoma City, OK 73154 | Oil & Gas Operator | Apr 2017 |
| 568 | Marshall Oil LLC | Eureka, KS 67045 | Oil Operator | Sep 2025 |
| 569 | Marshall Petroleum, Inc. | Houston, TX 77040 | Oil & Gas Operator | Aug 2003 |
| 570 | Marshall Pipe & Supply Co. | Nocona, TX 76255 | Oil & Gas Operator | Mar 2008 |
| 571 | Marshall Prod. & Energy Inc. | | Oil & Gas Operator | Jan 1992 |
| 572 | Marshall Production Co Inc | | Oil & Gas Operator | Jun 1989 |
| 573 | Marshall R Young Oil Co | Fort Worth, TX 76102 | Oil & Gas Operator | Feb 1996 |
| 574 | Marshall R. Young Operating, LLC | Fort Worth, TX 76102 | Oil & Gas Operator | Dec 2025 |
| 575 | Marshall Richard R | Jeromesville, OH 44840 | Oil & Gas Operator | Dec 2023 |
| 576 | Marshall Young Oil Co | | Oil & Gas Operator | Jan 2007 |
| 577 | Marshall, A. B. | Houston, TX 77050 | Oil & Gas Operator | Sep 1995 |
| 578 | Marshall, Dale | | Gas Operator | Dec 1995 |
| 579 | Marshall, Sam | Granbury, TX 76048 | Oil & Gas Operator | Aug 2010 |
| 580 | Marshall, Samuel Meek, Estate Of | Granbury, TX 76048 | Oil & Gas Operator | Dec 2025 |
| 581 | Marshco Production LLC | Colorado City, TX 79512 | Oil Operator | Dec 2025 |
| 582 | Marshel Inv | | Oil Operator | Oct 1991 |
| 583 | Marshfield Oil & Gas, LLC | Houston, TX 77070 | Oil & Gas Operator | Dec 2025 |
| 584 | Marshland Exploration Company | | Oil & Gas Operator | May 2006 |
| 585 | Martec Petroleum | | Oil Operator | Jan 1984 |
| 586 | Martens & Peck Operating Co | | Gas Operator | Feb 1997 |
| 587 | Martens & Peck Production Co | Denver, CO 80222 | Oil & Gas Operator | Feb 1997 |
| 588 | Martex Oil & Gas, Inc. | Estes Park, CO 80517 | Oil & Gas Operator | Dec 2025 |
| 589 | Martin & Richards Oil Co. | Jacksboro, TX 76458 | Oil & Gas Operator | Jul 1995 |
| 590 | Martin Billy G | Okmulgee, OK 74447 | Oil & Gas Operator | May 2013 |
| 591 | Martin Bros. Oil | Graham, TX 76450 | Oil & Gas Operator | Dec 1993 |
| 592 | Martin Burt K | Henryetta, OK 74437 | Oil & Gas Operator | Jul 2008 |
| 593 | Martin Cannon Interests, LLC | Kilgore, TX 75663 | Oil & Gas Operator | Dec 2025 |
| 594 | Martin Energy LLC | | Oil & Gas Operator | Apr 2023 |
| 595 | Martin Exploration | Westminster, CO 80030 | Oil & Gas Operator | Dec 1993 |
| 596 | Martin Exploration Co. | | Oil & Gas Operator | Apr 1986 |
| 597 | Martin Family Living Revocable Trust | Konawa, OK 74849-2221 | Oil Operator | Jul 2025 |
| 598 | Martin Foree Operating II, LLC | Royse City, TX 75189 | Oil & Gas Operator | Dec 2025 |
| 599 | Martin Foree Operating, LLC | Royse City, TX 75189 | Oil & Gas Operator | Dec 2025 |
| 600 | Martin Gas Sales, Inc. | Kilgore, TX 75662 | Oil & Gas Operator | May 1993 |