| 501 | Little Drop Oil Company | Graham, TX 76450 | Oil & Gas Operator | Feb 2026 |
| 502 | Littlepage, Tommy | Graham, TX 76450 | Oil & Gas Operator | May 1996 |
| 503 | LKM Oil & Gas | Jacksboro, TX 76458 | Oil & Gas Operator | Sep 2024 |
| 504 | LKM Oil And Gas LLC | Jacksboro, TX 76458 | Oil & Gas Operator | Feb 2026 |
| 505 | Lode Holdings, LLC | Wichita Falls, TX 76301 | Oil Operator | Feb 2026 |
| 506 | London Petroleum Corporation | Wichita Falls, TX 76307 | Oil & Gas Operator | Feb 2026 |
| 507 | Long, Edgar E. | Windthorst, TX 76389 | Oil & Gas Operator | Oct 2011 |
| 508 | Longhorn Oil Properties, Inc. | Pottsboro, TX 75076 | Oil & Gas Operator | Feb 2026 |
| 509 | Lorac, Inc. | Dallas, TX 75252 | Oil & Gas Operator | Feb 2026 |
| 510 | Los Hijos De Sanchez J LLC | Beeville, TX 78102 | Oil Operator | Feb 2026 |
| 511 | Lowrance, Gene | Chico, TX 76431 | Oil & Gas Operator | Aug 2003 |
| 512 | Lufkin Production Company Inc. | Jacksboro, TX 76458 | Oil & Gas Operator | Feb 2026 |
| 513 | Lynco Production Company | Dallas, TX 75243 | Oil & Gas Operator | Nov 1999 |
| 514 | Lynn Creek Energy | McKinney, TX 75071 | Oil & Gas Operator | Nov 2015 |
| 515 | Lynn Creek Oil Company | Allen, TX 75002 | Oil & Gas Operator | Apr 2020 |
| 516 | Lynn Creek Oil Partnership, II | Dallas, TX 75243 | Oil & Gas Operator | Oct 2003 |
| 517 | Lynn Creek Production Company | Allen, TX 75002 | Oil & Gas Operator | Dec 2011 |
| 518 | Lynx Oil Co., Inc. | Denton, TX 76207 | Oil & Gas Operator | Sep 2003 |
| 519 | Lynx Operating Co., Inc. | Dallas, TX 75206 | Oil & Gas Operator | Feb 2026 |
| 520 | Lyon Operating Company Inc.(Iii) | Jacksboro, TX 76458 | Oil & Gas Operator | Feb 2026 |
| 521 | M & A Oil Company, LTD. | Wichita Falls, TX 76307 | Oil & Gas Operator | Feb 2026 |
| 522 | M-B Operating Co., Inc. | Rowlett, TX 75030 | Oil & Gas Operator | Feb 2026 |
| 523 | Maddox Operating | Graham, TX 76450 | Oil & Gas Operator | Feb 2026 |
| 524 | Maguire Oil Company | Dallas, TX 75270 | Oil & Gas Operator | Mar 2015 |
| 525 | Mammoth Operating LLC | Spicewood, TX 78669 | Oil Operator | Feb 2026 |
| 526 | Maralo, Inc. | Midland, TX 79702 | Oil & Gas Operator | Dec 1998 |
| 527 | Marchman, J. E. | Graham, TX 76450 | Oil & Gas Operator | Jul 2009 |
| 528 | Marcon Operating Company, Inc. | Bridgeport, TX 76426 | Oil & Gas Operator | Oct 2011 |
| 529 | Marrow, N. S. | Austin, TX 78703 | Oil & Gas Operator | Aug 2012 |
| 530 | Marshall, Sam | Granbury, TX 76048 | Oil & Gas Operator | Aug 2010 |
| 531 | Marshall, Samuel Meek, Estate Of | Granbury, TX 76048 | Oil & Gas Operator | Feb 2026 |
| 532 | Martin & Richards Oil Co. | Jacksboro, TX 76458 | Oil & Gas Operator | Jul 1995 |
| 533 | Martin Bros. Oil | Graham, TX 76450 | Oil & Gas Operator | Dec 1993 |
| 534 | Martin Petroleum Corp. | Graham, TX 76450 | Oil & Gas Operator | Feb 2026 |
| 535 | Martin Well Service | Graham, TX 76450 | Oil & Gas Operator | Jun 2015 |
| 536 | Martin, John I. | Graham, TX 76450 | Oil & Gas Operator | Feb 2026 |
| 537 | Martin, Tim | Wichita Falls, TX 76302 | Oil & Gas Operator | Oct 2003 |
| 538 | Marwell Petroleum LTD Partnrship | Houston, TX 77027 | Oil & Gas Operator | Feb 2026 |
| 539 | Mash Oilfield Services, LP | Graham, TX 76450 | Oil & Gas Operator | Feb 2026 |
| 540 | Mattox, J. R. | Jacksboro, TX 76458 | Oil Operator | Mar 2018 |
| 541 | Mayco Oil | Nocona, TX 76255 | Oil & Gas Operator | Feb 2026 |
| 542 | Mayfield Engineering Service | Tulsa, OK 74104 | Oil & Gas Operator | Feb 2026 |
| 543 | Maynard Oil Co. | Denver, CO 80202 | Oil & Gas Operator | Sep 2004 |
| 544 | Mayo, Eddie | Fredericksbrg, TX 78624 | Oil & Gas Operator | Feb 2026 |
| 545 | MB Operating | Wichita Falls, TX 76309 | Oil & Gas Operator | Mar 2008 |
| 546 | McClymond, Inc. | Breckenridge, TX 76424 | Oil & Gas Operator | Jul 2001 |
| 547 | McClymond, LTD. | Breckenridge, TX 76424 | Oil & Gas Operator | Dec 2009 |
| 548 | McCommons Oil Company | Dallas, TX 75201 | Oil & Gas Operator | Feb 2026 |
| 549 | McCormick Operating, L.L.C. | Olney, TX 76374 | Oil Operator | Sep 2015 |
| 550 | McCracken, Eugene | Graham, TX 76450 | Oil & Gas Operator | Feb 2026 |
| 551 | McCracken, H. L. Company | Wichita Falls, TX 76308 | Oil & Gas Operator | Feb 2026 |
| 552 | McCutchin Petroleum Corporation | Dallas, TX 75225 | Oil & Gas Operator | Feb 2026 |
| 553 | McDay Energy Corp. | Dallas, TX 75206 | Oil & Gas Operator | Feb 2026 |
| 554 | McDonald Production | Lubbock, TX 79408 | Oil & Gas Operator | Mar 2003 |
| 555 | McEuen, Billy Oil Co. | Bowie, TX 76230 | Oil & Gas Operator | Dec 2016 |
| 556 | McEver Oil Company Inc. | Austin, TX 78789 | Oil & Gas Operator | Mar 2008 |
| 557 | MCG Oil & Gas Operating, LLC | Archer City, TX 76351 | Oil & Gas Operator | Sep 2023 |
| 558 | McKee, Kenneth W. Oil Co. | Graham, TX 76450 | Oil & Gas Operator | Aug 2011 |
| 559 | McMahon-Bullington Drilling Co. | Wichita Falls, TX 76307 | Oil & Gas Operator | Mar 1996 |
| 560 | McMahon-Bullington LP | Wichita Falls, TX 76307 | Oil & Gas Operator | Apr 2009 |
| 561 | Meeker, Dan Management, Inc. | Fort Worth, TX 76107 | Oil & Gas Operator | Aug 2007 |
| 562 | Melrose Operating Company | Dallas, TX 75201 | Oil & Gas Operator | Sep 2011 |
| 563 | Menasco, J. | Wichita Falls, TX 76310 | Oil & Gas Operator | Dec 2019 |
| 564 | Merit Energy Company | Dallas, TX 75240 | Oil & Gas Operator | Feb 2026 |
| 565 | Metis Energy LLC | Houston, TX 77019 | Oil & Gas Operator | Feb 2026 |
| 566 | MHM Oil Co. | Dallas, TX 75240 | Oil & Gas Operator | Oct 2002 |
| 567 | MHM Pipeline Co., Inc. | Dallas, TX 75252 | Oil & Gas Operator | Feb 2026 |
| 568 | Milagro Exploration, LLC | Houston, TX 77010 | Oil & Gas Operator | Aug 2018 |
| 569 | Miles Production Co. | Argyle, TX 76226 | Oil & Gas Operator | Mar 2008 |
| 570 | Miller, Bob I. | Abilene, TX 79604 | Oil & Gas Operator | Mar 2008 |
| 571 | Mills Oil & Gas | Jacksboro, TX 76458 | Oil & Gas Operator | Mar 2008 |
| 572 | Mitchell Energy Company L.P. | Spring, TX 77387 | Oil & Gas Operator | Mar 2008 |
| 573 | Mitchell Energy Corp | Houston, TX 77002 | Oil & Gas Operator | Aug 2013 |
| 574 | MKS Consulting Corporation | Weatherford, TX 76086 | Oil & Gas Operator | Jul 2005 |
| 575 | MKS Natural Gas Company | Weatherford, TX 76086 | Oil & Gas Operator | Mar 2016 |
| 576 | Mna Enterprises LTD. Co. | Hobbs, NM 88242 | Oil & Gas Operator | Oct 2025 |
| 577 | Mobil Oil Corporation | Houston, TX 77210 | Oil & Gas Operator | Dec 2007 |
| 578 | Mobil Petro Vac, Inc. | Duncan, OK 73533 | Oil & Gas Operator | Feb 2026 |
| 579 | Mobile Petrovac, Inc. | Wichita Falls, TX 76307 | Oil & Gas Operator | Feb 2026 |
| 580 | Mohican Exploration, LLC | Graham, TX 76450 | Oil & Gas Operator | Oct 2024 |
| 581 | Mokan Capital, LLC | Spicewood, TX 78669 | Oil Operator | Feb 2026 |
| 582 | Moller, Herbert T. | Wichita Falls, TX 76301 | Oil & Gas Operator | Aug 2003 |
| 583 | Moore, Stephen Operating | Graham, TX 76450 | Oil & Gas Operator | Jun 2002 |
| 584 | Morgan, C. V. Partnership | Olney, TX 76374 | Oil & Gas Operator | Jan 2009 |
| 585 | Moriah Resources, Inc. | Midland, TX 79704 | Oil & Gas Operator | Mar 2008 |
| 586 | Mortimer Production Company | San Antonio, TX 78209 | Oil & Gas Operator | Feb 2026 |
| 587 | Mosaic Oil LLC | Dallas, TX 75205 | Oil & Gas Operator | Feb 2026 |
| 588 | Mosaic Texas LLC | Dallas, TX 75205 | Oil & Gas Operator | Feb 2026 |
| 589 | Mote Resources, Inc. | Dallas, TX 75225 | Oil & Gas Operator | Dec 2004 |
| 590 | Mountain Creek Oil Company, Inc. | Saint Jo, TX 76265 | Oil & Gas Operator | Feb 2026 |
| 591 | Mullin, W. B. | Graham, TX 76450 | Oil & Gas Operator | Sep 1998 |
| 592 | Munson, David M. Inc. | Dallas, TX 75251 | Oil & Gas Operator | Feb 2026 |
| 593 | Murjo Oil & Royalty Company | Fort Worth, TX 76121 | Oil & Gas Operator | Aug 2025 |
| 594 | Myers, A. J. | Jacksboro, TX 76458 | Oil & Gas Operator | Feb 2026 |
| 595 | N. E. Operating Co., Inc. | Graham, TX 76450 | Oil & Gas Operator | Feb 2013 |
| 596 | Nall Oil & Gas | Mineral Wells, TX 76067 | Oil & Gas Operator | Feb 2026 |
| 597 | Natural Petroleum Company | Overton, TX 75684 | Oil & Gas Operator | Jun 1994 |
| 598 | Nautilus Exploration, Inc. | Farmers BRNCH, TX 75234 | Oil & Gas Operator | Nov 2021 |
| 599 | Ness Operating Of Texas, Inc. | Weatherford, TX 76087 | Oil & Gas Operator | Dec 2004 |
| 600 | New Era International | Graham, TX 76450 | Oil & Gas Operator | Sep 2017 |