| 401 | Morrison Oil Company | Bartlesville, OK 74003 | Oil Operator | Mar 2015 |
| 402 | Morton Bros A Partnership | Bristow, OK 74010-0403 | Oil & Gas Operator | Jul 2003 |
| 403 | Morton Brothers Company | Bristow, OK 74010 | Oil & Gas Operator | May 2009 |
| 404 | Morton Drilling Company | Bristow, OK 74010-1279 | Oil & Gas Operator | Jun 1995 |
| 405 | Morton Leases | Morris, OK 74445-2048 | Oil & Gas Operator | Jul 2017 |
| 406 | Morton Leases Inc | | Oil & Gas Operator | Oct 2025 |
| 407 | Morton Production Inc | Ada, OK 74820-2643 | Oil & Gas Operator | Sep 2014 |
| 408 | Moss Ted A Operating Company | Oklahoma City, OK 73126-0187 | Oil & Gas Operator | Jun 1997 |
| 409 | Moss William Properties Inc | Dallas, TX 75219 | Oil & Gas Operator | Apr 2014 |
| 410 | Mote Resources, Inc. | Dallas, TX 75225 | Oil & Gas Operator | Dec 2004 |
| 411 | Mott Energy LLC | Riverview, FL 33569-6702 | Oil & Gas Operator | Sep 2024 |
| 412 | Mott Oil & Gas | Sugarland, TX 77478 | Oil & Gas Operator | May 2001 |
| 413 | Mott Petroleum Corporation | Sugar Land, TX 77487 | Oil & Gas Operator | Aug 2024 |
| 414 | Mountain Creek Energy Inc | Georgetown, TX 78633 | Oil & Gas Operator | Sep 2025 |
| 415 | Mowdy Robert F | Coalgate, OK 74538 | Oil & Gas Operator | May 2001 |
| 416 | Mozark Corporation | Spring, TX 77379-8049 | Oil & Gas Operator | Jan 2011 |
| 417 | Moze Inc | Ochelata, OK 74051 | Oil & Gas Operator | Jan 2001 |
| 418 | MRD Nowata LLC | Woodstock, GA 30189 | Oil Operator | Aug 2017 |
| 419 | MSB Operating Company | Enid, OK 73703 | Oil & Gas Operator | Jan 2005 |
| 420 | MT Dora Energy Corporation | Duncan, OK 73533-1829 | Oil & Gas Operator | Apr 2014 |
| 421 | MT Dora Energy LLC | Houston, OK 77056-1940 | Oil & Gas Operator | Jun 2019 |
| 422 | MT Energy LLC | Waskom, TX 75692 | Oil & Gas Operator | Dec 2025 |
| 423 | Mto Oil Company | Okay, OK 74446-0354 | Oil Operator | Jul 2019 |
| 424 | Mud Operations Inc | Ames, OK 73718-9501 | Oil & Gas Operator | Nov 2025 |
| 425 | Muegge Don E | Lamont, OK 74643-5010 | Oil & Gas Operator | Dec 1996 |
| 426 | Mueggenborg Derrick R Dba DRM Oil & Gas | Yale, OK 74085 | Oil Operator | Oct 2025 |
| 427 | Mueller Thomas C | Fort Smith, AR 72913 | Gas Operator | Aug 2008 |
| 428 | Mueller Thomas C LTD | Oklahoma City, OK 73102-5683 | Gas Operator | Aug 2008 |
| 429 | Muirfield Resources Company | Tulsa, OK 74101-3166 | Oil & Gas Operator | Jun 2024 |
| 430 | Mullen William Company | Edmond, OK 73083-1372 | Oil & Gas Operator | May 1999 |
| 431 | Mullins Jimmy R Dba Southcreek Petroleum Co | Dibble, OK 73031 | Oil & Gas Operator | Jan 2021 |
| 432 | Mullins, John S | | Oil Operator | Nov 2014 |
| 433 | Multistates Oil Properties, NV | Oklahoma City, OK 73112 | Oil & Gas Operator | Nov 1998 |
| 434 | Munson Dave Company | Dallas, TX 75201-3591 | Oil Operator | Aug 1996 |
| 435 | Munson, David M. | Dallas, TX 75201 | Oil & Gas Operator | Mar 2015 |
| 436 | Muras Energy Inc | Edmond, OK 73013 | Oil & Gas Operator | Oct 2025 |
| 437 | Murchison Oil & Gas Inc | Plano, TX 75024 | Oil & Gas Operator | Aug 2020 |
| 438 | Murexco Petroleum Inc | Dallas, TX 75251 | Oil & Gas Operator | Oct 1996 |
| 439 | Murphy Helen Colpitt Trust | Collinsville, OK 74021-0128 | Oil & Gas Operator | May 2002 |
| 440 | Murphy Jack L | Tulsa, OK 74104-4915 | Oil Operator | Mar 2015 |
| 441 | Musgrove Casey Oil | Ponca City, OK 74602-0391 | Oil & Gas Operator | Jun 2017 |
| 442 | Musgrove Energy Inc | Ponca City, OK 74602 | Oil & Gas Operator | Sep 2025 |
| 443 | Mustang Fuel Corp. Of Oklahoma | Oklahoma City, OK 73106 | Oil & Gas Operator | Nov 2016 |
| 444 | Mustang Fuel Corporation | Oklahoma City, OK 73114 | Oil & Gas Operator | Nov 2025 |
| 445 | Mustang Gas Products LLC | Oklahoma City, OK 73114-7406 | Oil & Gas Operator | Sep 2022 |
| 446 | Mutual Oil & Gas Co | Akron, OH 44311 | Oil & Gas Operator | Dec 2000 |
| 447 | MW Petroleum Corporation | Houston, TX 77056 | Oil & Gas Operator | Mar 2015 |
| 448 | MXP Operating LLC | Covington, TX 76093 | Oil & Gas Operator | Aug 2025 |
| 449 | Myers, Robert L | | Oil Operator | Oct 2025 |
| 450 | Myjo Oil Corporation | Breckenridge, TX 76024 | Oil Operator | Jul 1996 |
| 451 | Mystique Resources Company | Aurora, CO 80016 | Oil & Gas Operator | Feb 2023 |