| 401 | Kiamichi Oil & Gas | Whitehouse, TX 75791 | Oil Operator | Oct 1997 |
| 402 | Kimbell Operating Company | Fort Worth, TX 76102 | Oil & Gas Operator | Dec 2025 |
| 403 | King Operating Corporation | Fort Worth, TX 76147 | Oil & Gas Operator | Dec 2025 |
| 404 | Kingwood Resources, Inc. | Kingwood, TX 77339 | Oil & Gas Operator | May 2022 |
| 405 | Kiva Resources Inc. | Houston, TX 77265 | Oil & Gas Operator | Mar 2008 |
| 406 | KJ Energy, LLC | MT Enterprise, TX 75681 | Oil & Gas Operator | Jul 2024 |
| 407 | Klo Oil & Gas, L.L.C. | Tulsa, OK 74120 | Oil & Gas Operator | Jan 2023 |
| 408 | L & L Resources, Inc. | Hays, KS 67601 | Oil Operator | Mar 1986 |
| 409 | L & R Energy Corporation | Spearman, TX 79081 | Oil & Gas Operator | Nov 2014 |
| 410 | L & R Petroleum | Kilgore, TX 75663 | Oil & Gas Operator | Dec 2025 |
| 411 | L.C.S. Production Company | Abilene, TX 79608 | Oil & Gas Operator | Dec 2025 |
| 412 | Lake Ronel Oil Company | Tyler, TX 75710 | Oil & Gas Operator | Jul 2017 |
| 413 | Lancer Petroleum Corporation | Irving, TX 75014 | Oil & Gas Operator | Feb 2014 |
| 414 | Largo Oil Company | Longview, TX 75606 | Oil & Gas Operator | Dec 2025 |
| 415 | Lawton, Jack Inc. | Sulphur, LA 70663 | Oil & Gas Operator | Dec 1995 |
| 416 | Lease Holders Acquisitions LLC | Yukon, OK 73099 | Gas Operator | Dec 2025 |
| 417 | Lehnertz, G. M. | Tyler, TX 75702 | Oil & Gas Operator | Dec 1998 |
| 418 | Lehnertz-Faulkner, Inc. | Tyler, TX 75701 | Oil & Gas Operator | Feb 2023 |
| 419 | Leonard, Patricia Anne | San Antonio, TX 78209 | Oil & Gas Operator | Oct 1996 |
| 420 | Lillis, Michael D. | Midland, TX 79702 | Oil & Gas Operator | Dec 2025 |
| 421 | Linder, John G. Jr. | Gladewater, TX 75647 | Oil & Gas Operator | Apr 2005 |
| 422 | Linder, John Operating Co., LLC | Gladewater, TX 75647 | Oil & Gas Operator | Dec 2025 |
| 423 | Little & Whyte Operating, Inc. | Tyler, TX 75711 | Oil & Gas Operator | Mar 2008 |
| 424 | LKD Corp. | Kilgore, TX 75663 | Oil & Gas Operator | Apr 2018 |
| 425 | Log Operating, LLC | Eagle Pass, TX 78853 | Oil & Gas Operator | Dec 2025 |
| 426 | Loin Energy Corporation | La Grange, TX 78945 | Oil & Gas Operator | Dec 2025 |
| 427 | Long Trusts, The | Kilgore, TX 75663 | Oil & Gas Operator | Dec 2025 |
| 428 | Long, Larry T. | Kilgore, TX 75663 | Oil & Gas Operator | Jun 2017 |
| 429 | Long-Tex Exploration, Inc. | Kilgore, TX 75662 | Oil & Gas Operator | Dec 2025 |
| 430 | Longview Production, Inc. | Kilgore, TX 75663 | Oil & Gas Operator | Dec 2002 |
| 431 | Louisiana Land & Exploration Co. | Houston, TX 77210 | Oil & Gas Operator | Sep 2013 |
| 432 | Low-End Oil LLC | Austin, TX 78748 | Oil Operator | Dec 2025 |
| 433 | LTS Oil & Gas | Lubbock, TX 79424 | Oil & Gas Operator | Dec 2025 |
| 434 | LTS Oil & Gas A | Lubbock, TX 79424 | Oil & Gas Operator | Dec 2025 |
| 435 | M & G Oil Company | Marble Falls, TX 78654 | Oil & Gas Operator | Dec 2025 |
| 436 | M & M Construction Co. | Kilgore, TX 75663 | Oil & Gas Operator | Jan 1996 |
| 437 | M A S Operators | Kilgore, TX 75663 | Oil & Gas Operator | Jul 1999 |
| 438 | M-C Production & Drilling Co,Inc | Longview, TX 75608 | Oil & Gas Operator | Dec 2025 |
| 439 | M. E. Operating & Services, Inc. | Fort Worth, TX 76104 | Oil & Gas Operator | Dec 2025 |
| 440 | M. Grace, Inc. | Henderson, TX 75653 | Oil & Gas Operator | Dec 2025 |
| 441 | M. J. G., Inc. | Alice, TX 78333 | Oil & Gas Operator | Jul 2010 |
| 442 | Machin & Associates, Inc. | Longview, TX 75606 | Oil & Gas Operator | Dec 2025 |
| 443 | Manziel Management Corporation | Tyler, TX 75711 | Oil Operator | Feb 2014 |
| 444 | Map Production Co., Inc. | Kilgore, TX 75663 | Oil & Gas Operator | Dec 2025 |
| 445 | Marathon Oil Company | Houston, TX 77252 | Oil & Gas Operator | Oct 2025 |
| 446 | Marquee Corporation | Houston, TX 77024 | Oil & Gas Operator | Dec 2025 |
| 447 | Marshall R. Young Operating, LLC | Fort Worth, TX 76102 | Oil & Gas Operator | Dec 2025 |
| 448 | Martin Gas Sales, Inc. | Kilgore, TX 75662 | Oil & Gas Operator | May 1993 |
| 449 | Martineau Petroleum, Inc. | Dallas, TX 75206 | Oil & Gas Operator | Jan 2025 |
| 450 | Mass Energy, Inc | Houston, TX 77056 | Oil & Gas Operator | Mar 2008 |
| 451 | Matador Operating Company | Dallas, TX 75240 | Oil & Gas Operator | Jul 2003 |
| 452 | Maxima Energy Corp. | Kilgore, TX 75663 | Oil & Gas Operator | Sep 2012 |
| 453 | Maximus Operating, LTD. | Kilgore, TX 75663 | Oil & Gas Operator | Dec 2025 |
| 454 | Maxwell Oil & Gas Corp. | Kilgore, TX 75663 | Oil & Gas Operator | Jan 2001 |
| 455 | Maxwell, J. K. | Kilgore, TX 75662 | Oil & Gas Operator | Aug 1995 |
| 456 | Mayo, Eddie | Fredericksbrg, TX 78624 | Oil & Gas Operator | Dec 2025 |
| 457 | McBee Operating Company, L.L.C. | Dallas, TX 75209 | Oil & Gas Operator | Dec 2025 |
| 458 | McBrayer Oil Corporation | Rockport, TX 78381 | Oil & Gas Operator | Nov 1994 |
| 459 | McBride Operating LLC | Kilgore, TX 75663 | Oil & Gas Operator | Dec 2025 |
| 460 | McBride, Jerrel L Enterprise Inc | Kilgore, TX 75663 | Oil & Gas Operator | Jun 1999 |
| 461 | McDaniel Company, Inc., The | Dallas, TX 75230 | Oil & Gas Operator | Dec 2025 |
| 462 | McFarland Energy, Inc. | New Orleans, LA 70160 | Oil & Gas Operator | Dec 2009 |
| 463 | McGoldrick Oil Company | Shreveport, LA 71129 | Oil & Gas Operator | Jul 2020 |
| 464 | McMurrey, R. J., Production Comp | Tyler, TX 75711 | Oil & Gas Operator | Dec 2025 |
| 465 | Meadows Oil Company | Plano, TX 75075 | Oil & Gas Operator | Aug 2004 |
| 466 | Memorial Production Operating LLC | Houston, TX 77002 | Oil & Gas Operator | Dec 2025 |
| 467 | Meridian Oil Inc. | Houston, TX 77210 | Oil & Gas Operator | Aug 1996 |
| 468 | Merit Energy Company | Dallas, TX 75240 | Oil & Gas Operator | Dec 2025 |
| 469 | Mewbourne Oil Company | Tyler, TX 75711 | Oil & Gas Operator | Dec 2025 |
| 470 | Mexco Energy Corporation | Midland, TX 79702 | Oil & Gas Operator | Feb 2020 |
| 471 | Midcoast G & P (East Texas) L.P. | Houston, TX 77002 | Oil & Gas Operator | Dec 2025 |
| 472 | Miken Oil, Inc. | Kilgore, TX 75663 | Oil & Gas Operator | Dec 2025 |
| 473 | Miller Energy Inc | Houston, TX 77024 | Oil & Gas Operator | Oct 2016 |
| 474 | Miller Production Co. | Tyler, TX 75701 | Oil & Gas Operator | Dec 2025 |
| 475 | Miller, R. A. Energy, Inc. | Kilgore, TX 75663 | Oil & Gas Operator | Aug 2003 |
| 476 | Mission Resources Corporation | Houston, TX 77002 | Oil & Gas Operator | Mar 2008 |
| 477 | MJ Energy Company, LLC | Kilgore, TX 75663 | Oil Operator | Dec 2025 |
| 478 | MMGL East Texas III, LLC | Dallas, TX 75240 | Oil & Gas Operator | Dec 2025 |
| 479 | Mobil Producing TX. & N.M. Inc. | Spring, TX 77389 | Oil & Gas Operator | Dec 2025 |
| 480 | Montgomery Petroleum, Inc. | Dallas, TX 75206 | Oil & Gas Operator | Aug 2007 |
| 481 | Moon Operating, Inc. | Longview, TX 75601 | Oil & Gas Operator | Mar 2003 |
| 482 | Morgan Oil Company | Nacogdoches, TX 75963 | Oil & Gas Operator | May 2006 |
| 483 | Moss Petroleum Company | Dallas, TX 75207 | Oil & Gas Operator | Dec 2025 |
| 484 | Mud Creek Operating, LLC | Tyler, TX 75702 | Oil & Gas Operator | Dec 2025 |
| 485 | Muras Energy Inc | Edmond, OK 73013 | Oil & Gas Operator | Aug 2025 |
| 486 | Murphy Exploration & Prod. Co. | Houston, TX 77094 | Oil & Gas Operator | Jun 2011 |
| 487 | Murphy Oil USA, Inc. | New Orleans, LA 70161 | Oil & Gas Operator | Jan 1993 |
| 488 | Mustang Drilling, Inc. | Henderson, TX 75653 | Oil & Gas Operator | Aug 2024 |
| 489 | Mustang Drilling, LTD. | Henderson, TX 75653 | Oil & Gas Operator | May 2008 |
| 490 | Mustang Energy Inc. | Porter, TX 77365 | Oil & Gas Operator | Mar 2008 |
| 491 | Mustang Operating Company | Kilgore, TX 75663 | Oil & Gas Operator | Apr 2006 |
| 492 | MW Petroleum Corporation | Houston, TX 77056 | Oil & Gas Operator | Mar 2015 |
| 493 | Nadel & Gussman | Tulsa, OK 74103 | Oil & Gas Operator | May 2007 |
| 494 | Nadel And Gussman LLC | Tulsa, OK 74119 | Oil & Gas Operator | Dec 2025 |
| 495 | National Energy Group Inc | Dallas, TX 75206 | Oil & Gas Operator | Sep 2014 |
| 496 | National Onshore LP | Oklahoma City, OK 73102 | Oil & Gas Operator | Mar 2008 |
| 497 | Natural Petroleum Company | Overton, TX 75684 | Oil & Gas Operator | Jun 1994 |
| 498 | Neches Oil & Gas Company, Inc. | Kilgore, TX 75663 | Oil & Gas Operator | Dec 2025 |
| 499 | Neff, Harold & Associates, Inc. | Tyler, TX 75702 | Oil & Gas Operator | May 2008 |
| 500 | Neg Operating LLC | Oklahoma City, OK 73101 | Oil & Gas Operator | Aug 2025 |