| 501 | Langford, G. E. | Abilene, TX 79604 | Oil & Gas Operator | Jan 2002 |
| 502 | Lankford, Dan L. | Graham, TX 76450 | Oil & Gas Operator | Dec 2025 |
| 503 | Leonard Brothers Operating Co. | Fort Worth, TX 76101 | Oil & Gas Operator | Dec 2025 |
| 504 | Lewis Heirs 480, LLC | Bryson, TX 76427 | Oil & Gas Operator | Dec 2025 |
| 505 | Lewis Operating Company | Holliday, TX 76366 | Oil & Gas Operator | Dec 2025 |
| 506 | Lewis, William T. | Graham, TX 76450 | Oil & Gas Operator | Mar 2008 |
| 507 | Lex And Lace Petroleum, LLC | Houston, TX 77269 | Oil Operator | Dec 2025 |
| 508 | Lindemann, James D. | Holliday, TX 76366 | Oil & Gas Operator | Mar 2008 |
| 509 | Lindemann, W. L., DRLG. Co. | Wichita Falls, TX 76308 | Oil & Gas Operator | Jun 1994 |
| 510 | Lindemann, W.L., Oper. Co., Inc. | Wichita Falls, TX 76308 | Oil & Gas Operator | Apr 2006 |
| 511 | Lindley, J. R. | Richardson, TX 75081 | Oil & Gas Operator | Jun 2002 |
| 512 | Lindsay Oil Operations | Wichita Falls, TX 76310 | Oil & Gas Operator | Jun 2010 |
| 513 | Lindsay, Dick | Graham, TX 76450 | Oil & Gas Operator | May 2015 |
| 514 | Little Drop Oil Company | Graham, TX 76450 | Oil & Gas Operator | Dec 2025 |
| 515 | Little, Quintin Company,Inc.,The | Ardmore, OK 73402 | Oil & Gas Operator | Dec 2025 |
| 516 | Littlepage, Tommy | Graham, TX 76450 | Oil & Gas Operator | May 1996 |
| 517 | Live Oak Gas Company | Dallas, TX 75251 | Oil & Gas Operator | Dec 2025 |
| 518 | Livingston, David Oil Company | Haskell, TX 79521 | Oil & Gas Operator | Aug 2003 |
| 519 | Lonestar Production Services | Graham, TX 76450 | Oil Operator | Dec 2025 |
| 520 | Long Trusts, The | Kilgore, TX 75663 | Oil & Gas Operator | Dec 2025 |
| 521 | Lucky Oil & Gas | Malibu, CA 90265 | Oil & Gas Operator | Dec 2025 |
| 522 | Lunn, Will | Wichita Falls, TX 76301 | Oil & Gas Operator | Jun 1997 |
| 523 | Lyon Operating Company Inc.(Iii) | Jacksboro, TX 76458 | Oil & Gas Operator | Dec 2025 |
| 524 | M2 Squared Operating, LLC | Rockwall, TX 75032 | Oil Operator | Dec 2025 |
| 525 | Mac Operating | Graham, TX 76450 | Oil & Gas Operator | Jun 2023 |
| 526 | Maddox Operating | Graham, TX 76450 | Oil & Gas Operator | Dec 2025 |
| 527 | Maddux Oil & Gas | Strawn, TX 76475 | Oil & Gas Operator | Dec 2025 |
| 528 | Madera, R. F. | Palm Desert, CA 92210 | Oil & Gas Operator | Sep 2000 |
| 529 | Magnum Production & Well Service | Iowa Park, TX 76367 | Oil & Gas Operator | Dec 2025 |
| 530 | Mahler & Scott | Ruidoso, NM 88355 | Oil & Gas Operator | Aug 2003 |
| 531 | Mahler, Kelly Operating | Graham, TX 76450 | Oil & Gas Operator | Mar 2017 |
| 532 | Maledon Enterprises | Austin, TX 78738 | Oil & Gas Operator | Feb 1996 |
| 533 | Mammoth Operating LLC | Spicewood, TX 78669 | Oil Operator | Dec 2025 |
| 534 | Maranatha Exploration, LP | Wichita Falls, TX 76307 | Oil Operator | Feb 2012 |
| 535 | Marbil Oil, Inc. | Olney, TX 76374 | Oil & Gas Operator | Jun 2013 |
| 536 | Marchman, J. E. | Graham, TX 76450 | Oil & Gas Operator | Jul 2009 |
| 537 | Marcon Operating Company, Inc. | Bridgeport, TX 76426 | Oil & Gas Operator | Oct 2011 |
| 538 | Marjac Oil Company, Inc. | Breckenridge, TX 76424 | Oil & Gas Operator | Dec 2025 |
| 539 | Marshall Energy, Inc. | Dallas, TX 75243 | Oil & Gas Operator | May 1997 |
| 540 | Marshall Pipe & Supply Co. | Nocona, TX 76255 | Oil & Gas Operator | Mar 2008 |
| 541 | Martin Bros. Oil | Graham, TX 76450 | Oil & Gas Operator | Dec 1993 |
| 542 | Martin Petroleum Corp. | Graham, TX 76450 | Oil & Gas Operator | Dec 2025 |
| 543 | Martin Well Service | Graham, TX 76450 | Oil & Gas Operator | Jun 2015 |
| 544 | Martin, John I. | Graham, TX 76450 | Oil & Gas Operator | Dec 2025 |
| 545 | Martin, Pat Jr. | Archer City, TX 76351 | Oil & Gas Operator | Dec 2019 |
| 546 | Mash Oilfield Services, LP | Graham, TX 76450 | Oil & Gas Operator | Dec 2025 |
| 547 | Mathis & Sons, Inc. | Rule, TX 79547 | Oil & Gas Operator | Dec 2025 |
| 548 | Maverick Properties, Inc. | San Antonio, TX 78209 | Oil & Gas Operator | Sep 1994 |
| 549 | Mayco Oil | Nocona, TX 76255 | Oil & Gas Operator | Dec 2025 |
| 550 | Maynard Oil Co. | Denver, CO 80202 | Oil & Gas Operator | Sep 2004 |
| 551 | Mayo, Eddie | Fredericksbrg, TX 78624 | Oil & Gas Operator | Dec 2025 |
| 552 | MB Operating | Wichita Falls, TX 76309 | Oil & Gas Operator | Mar 2008 |
| 553 | MBX Operating LLC | Houston, TX 77007 | Oil & Gas Operator | Dec 2025 |
| 554 | McCauley Production | Graham, TX 76450 | Oil Operator | Dec 2025 |
| 555 | McClymond, Inc. | Breckenridge, TX 76424 | Oil & Gas Operator | Jul 2001 |
| 556 | McClymond, LTD. | Breckenridge, TX 76424 | Oil & Gas Operator | Dec 2009 |
| 557 | McCormick Operating, L.L.C. | Olney, TX 76374 | Oil Operator | Sep 2015 |
| 558 | McCown Engineering | Wichita Falls, TX 76310 | Oil & Gas Operator | Dec 2025 |
| 559 | McDaniel Company, Inc., The | Dallas, TX 75230 | Oil & Gas Operator | Dec 2025 |
| 560 | McDonald, Joe | Burkburnett, TX 76354 | Oil & Gas Operator | Aug 1995 |
| 561 | MCG Oil & Gas Operating, LLC | Archer City, TX 76351 | Oil & Gas Operator | Sep 2023 |
| 562 | McKee, Kenneth W. Oil Co. | Graham, TX 76450 | Oil & Gas Operator | Aug 2011 |
| 563 | McMahon-Bullington Drilling Co. | Wichita Falls, TX 76307 | Oil & Gas Operator | Mar 1996 |
| 564 | McRae Exploration & Prod., Inc. | Houston, TX 77064 | Oil & Gas Operator | Feb 2017 |
| 565 | Menasco, J. | Wichita Falls, TX 76310 | Oil & Gas Operator | Dec 2019 |
| 566 | Mercury Exploration Co. | Fort Worth, TX 76104 | Oil & Gas Operator | Dec 2006 |
| 567 | Merit Energy Company | Dallas, TX 75240 | Oil & Gas Operator | Dec 2025 |
| 568 | Mesquite Oil & Gas | Olney, TX 76374 | Oil & Gas Operator | Sep 2025 |
| 569 | MGM Oil & Gas Company | Midland, TX 79702 | Oil & Gas Operator | Dec 2025 |
| 570 | MHM Oil Co. | Dallas, TX 75240 | Oil & Gas Operator | Oct 2002 |
| 571 | Mi-Co Oil & Gas LLC | Caddo, TX 76429 | Oil Operator | Dec 2025 |
| 572 | Miller, Bob I. | Abilene, TX 79604 | Oil & Gas Operator | Mar 2008 |
| 573 | Miller, C. R. Oil Co. | Olney, TX 76374 | Oil & Gas Operator | Dec 2025 |
| 574 | Mitchell Drilling Co. | Iowa Park, TX 76367 | Oil & Gas Operator | Nov 2000 |
| 575 | Mitchell Energy Company L.P. | Spring, TX 77387 | Oil & Gas Operator | Mar 2008 |
| 576 | Mitchell Energy Corp | Houston, TX 77002 | Oil & Gas Operator | Aug 2013 |
| 577 | Mitchell Oil Company | Iowa Park, TX 76367 | Oil & Gas Operator | Nov 2000 |
| 578 | MJM Oil & Gas, Inc. | Dallas, TX 75201 | Oil & Gas Operator | Aug 2003 |
| 579 | MMD Oil Co. | Olney, TX 76374 | Oil & Gas Operator | Dec 2000 |
| 580 | Mogul Resources, LLC | Cisco, TX 76437 | Oil & Gas Operator | Dec 2025 |
| 581 | Mole Hole Prod. | Bridgeport, TX 76426 | Oil Operator | Dec 2025 |
| 582 | Momentum Oil Company | Albany, TX 76430 | Oil & Gas Operator | May 2003 |
| 583 | Monarch Operating Company | Graham, TX 76450 | Oil & Gas Operator | Jun 2006 |
| 584 | Mont-Land Co. | Graham, TX 76450 | Oil & Gas Operator | Mar 2008 |
| 585 | Montgomery Petroleum, Inc. | Dallas, TX 75206 | Oil & Gas Operator | Aug 2007 |
| 586 | Moore, Stephen Operating | Graham, TX 76450 | Oil & Gas Operator | Jun 2002 |
| 587 | Morgan, C. V. Partnership | Olney, TX 76374 | Oil & Gas Operator | Jan 2009 |
| 588 | Moriah Resources, Inc. | Midland, TX 79704 | Oil & Gas Operator | Mar 2008 |
| 589 | Mortimer Exploration Company | San Antonio, TX 78209 | Oil & Gas Operator | Sep 2003 |
| 590 | Mortimer Production Company | San Antonio, TX 78209 | Oil & Gas Operator | Dec 2025 |
| 591 | Mosaic Oil LLC | Dallas, TX 75205 | Oil & Gas Operator | Dec 2025 |
| 592 | Mosaic Texas LLC | Dallas, TX 75205 | Oil & Gas Operator | Dec 2025 |
| 593 | Mosman Operating, LLC | Dallas, TX 75204 | Oil Operator | Dec 2025 |
| 594 | Mote Resources, Inc. | Dallas, TX 75225 | Oil & Gas Operator | Dec 2004 |
| 595 | Mueller Engineering Corp. | Corpus Chrsti, TX 78476 | Oil & Gas Operator | Feb 2002 |
| 596 | Mullin, W. B. | Graham, TX 76450 | Oil & Gas Operator | Sep 1998 |
| 597 | Mullins, Manuel | Olney, TX 76374 | Oil & Gas Operator | Dec 2025 |
| 598 | Myers, James B. | Olney, TX 76374 | Oil & Gas Operator | Dec 2025 |
| 599 | N C B Oil Company | Graham, TX 76450 | Oil & Gas Operator | Dec 2025 |
| 600 | N. E. Operating Co., Inc. | Graham, TX 76450 | Oil & Gas Operator | Feb 2013 |