| 301 | Mallard Oil & Gas | Cody, WY 82414-9640 | Oil & Gas Operator | Oct 2019 |
| 302 | Mallard Operating LLC | | Oil & Gas Operator | Nov 2024 |
| 303 | Mallard Petroleum, Inc. | | Oil & Gas Operator | Apr 1986 |
| 304 | Mallett Luke-Dba Mallett Energy | New Concord, OH 43762 | Oil & Gas Operator | Dec 2016 |
| 305 | Mallon Oil Company | Denver, CO 80202 | Oil & Gas Operator | Jun 2005 |
| 306 | Mallorn Energy LLC | Edmond, OK 73034 | Oil & Gas Operator | Feb 2026 |
| 307 | Mallory, Meredith, Jr. | San Antonio, TX 78209 | Oil & Gas Operator | Jul 2002 |
| 308 | Malmac Energy Corp. | | Oil & Gas Operator | Jul 1987 |
| 309 | Malone Donald J | | Oil Operator | Nov 1993 |
| 310 | Malone Oil & Gas Exploration, Inc. | | Oil Operator | Dec 2018 |
| 311 | Malone Oil Co. | | Oil & Gas Operator | Jul 2006 |
| 312 | Malone Oil Compa | | Oil Operator | Dec 1994 |
| 313 | Malone Oil Production | La Vernia, TX 78121 | Oil & Gas Operator | Jun 2026 |
| 314 | Malone-Killen Oil Expl. Co. | | Oil Operator | Apr 1992 |
| 315 | Maloney Helen V Dba Penn-Ok Corporation | Hockessin, DE 19707-9640 | Oil & Gas Operator | Feb 2026 |
| 316 | Malpais Inc | Prague, OK 74864 | Gas Operator | Feb 2026 |
| 317 | Malson Oil Company | Crawford, OK 73638 | Oil & Gas Operator | Dec 2016 |
| 318 | Malvern Group Inc | Clearwater, FL 33758-6817 | Oil & Gas Operator | Mar 2005 |
| 319 | Maly & Maly Oil | Beggs, OK 74421-2844 | Oil & Gas Operator | Feb 2026 |
| 320 | Mamerow Energy Corp | Ganado, TX 77962 | Oil & Gas Operator | Jun 2026 |
| 321 | Mammoth Exploration LLC | Midland, TX 79701 | Oil & Gas Operator | Jul 2023 |
| 322 | Mammoth Operating LLC | Spicewood, TX 78669 | Oil Operator | Jun 2026 |
| 323 | Mammoth Service Group, LLC | | Oil & Gas Operator | Dec 2025 |
| 324 | Manana Gas Inc | Albuquerque, NM 87122 | Oil & Gas Operator | Mar 2026 |
| 325 | Mancal Resources Corporation | | Oil & Gas Operator | Aug 2019 |
| 326 | Mance, Patricia M. | Eden, NY 14057 | Gas Operator | Dec 2024 |
| 327 | Manchester Oil Co | | Oil Operator | Jan 2000 |
| 328 | Mancuso, Richard L. | Le Roy, NY 14482 | Gas Operator | Dec 2024 |
| 329 | Mandalay Oil & Gas, L.L.C. | | Oil & Gas Operator | May 2008 |
| 330 | Mandalay Trading Services Inc. | | Oil Operator | Jul 1999 |
| 331 | Mandarin Oil & Gas Company | Austin, TX 78714 | Oil & Gas Operator | Jun 2026 |
| 332 | Mandina & Murphy Oil Company | | Oil Operator | Nov 1990 |
| 333 | Mandujano, Alfonso & Olga | Von Ormy, TX 78073 | Oil & Gas Operator | Dec 2014 |
| 334 | Mandujano, Alfonso, Jr. | Von Ormy, TX 78073 | Oil Operator | Jun 2026 |
| 335 | Manewal Bradley Oil Company | Newcastle, WY 82701 | Oil & Gas Operator | Aug 2013 |
| 336 | Maney McNeal Oil & Gas | | Oil & Gas Operator | Dec 1999 |
| 337 | Manhattan Petroleum, Inc. | Midland, TX 79702 | Oil & Gas Operator | Jun 2026 |
| 338 | Manis Oil & Gas Inc | Blanchard, OK 73010 | Oil & Gas Operator | Dec 2025 |
| 339 | Manitou Explor Co Inc | Granville, OH 43023 | Oil & Gas Operator | Dec 1997 |
| 340 | Manley Energy Resources LLC | | Oil Operator | Jan 2018 |
| 341 | Manley, John D. III, Oper., Inc | Corpus Christ, TX 78404 | Oil & Gas Operator | Feb 2016 |
| 342 | Mann Energy, Inc. | Charleston, WV 25332-3242 | Oil & Gas Operator | Nov 2018 |
| 343 | Mann Oil Company, LLC | | Oil Operator | Jun 2023 |
| 344 | Mann Production Co., Inc. | | Oil Operator | Nov 1995 |
| 345 | Manna Corporation | Oklahoma City, OK 73162 | Oil & Gas Operator | Dec 2014 |
| 346 | Manna Minerals, Inc. | | Oil & Gas Operator | Apr 1989 |
| 347 | Manning, Gregory | Ellinwood, KS 67526 | Oil Operator | Feb 2026 |
| 348 | Manning, Jack | Odessa, TX 79760 | Oil & Gas Operator | Dec 2003 |
| 349 | Mannon L. Walters, Inc. | | Oil & Gas Operator | Jun 2024 |
| 350 | Manns' Atp, Inc. | Potwin, KS 67123 | Oil Operator | Oct 2025 |
| 351 | Manolo Energy, Inc. | | Oil Operator | Sep 1996 |
| 352 | Manorado Oil Company | | Oil Operator | Feb 1999 |
| 353 | Manta Petroleum, Inc. | Englewood, CO 80155 | Oil & Gas Operator | Jun 2020 |
| 354 | Mantex Inc | Tulsa, OK 74114-6234 | Oil & Gas Operator | Mar 2015 |
| 355 | Manti Exploration Operating LLC | Corpus Chrsti, TX 78403 | Oil & Gas Operator | Feb 2015 |
| 356 | Manti Operating Company | Covington, LA 70435 | Oil & Gas Operator | Jun 2026 |
| 357 | Manti Tarka Permian Op, LLC | Houston, TX 77056 | Oil & Gas Operator | Jun 2026 |
| 358 | Mantle Oil & Gas, LLC | Friendswood, TX 77546 | Oil & Gas Operator | Jun 2026 |
| 359 | Manuel Corporation | Wichita, KS 67206 | Oil & Gas Operator | Mar 2026 |
| 360 | Manursing Island Prod. Corp. | | Oil & Gas Operator | Sep 2002 |
| 361 | Manx Inc | Pleasantville, PA 16341-1229 | Oil Operator | Dec 2020 |
| 362 | Manx Oil Corporation | Casper, WY 82601 | Oil & Gas Operator | Jun 2010 |
| 363 | Manzanita Corporation | Midland, TX 79710 | Oil & Gas Operator | Nov 2008 |
| 364 | Manzanita Operating, LLC | Midland, TX 79702 | Oil & Gas Operator | Jun 2026 |
| 365 | Manzano Oil Corporation | Roswell, NM 88202 | Oil & Gas Operator | Feb 2005 |
| 366 | Manzano, LLC | Roswell, NM 88202 | Oil & Gas Operator | Jun 2026 |
| 367 | Manziel Interests | Tyler, TX 75711 | Oil & Gas Operator | Jun 2004 |
| 368 | Manziel Management Corporation | Tyler, TX 75711 | Oil Operator | Feb 2014 |
| 369 | Map Associates, L.P. | | Oil & Gas Operator | Mar 1995 |
| 370 | Map Drilling Company | | Oil & Gas Operator | Apr 2012 |
| 371 | Map Oil Co. | | Oil Operator | Jan 1978 |
| 372 | Map Production Co., Inc. | Kilgore, TX 75663 | Oil & Gas Operator | Jun 2026 |
| 373 | Mapco Inc | Billings, MT 59102 | Oil & Gas Operator | Dec 1983 |
| 374 | Mapco Oil & Gas Company | Tulsa, OK 74101-2115 | Oil & Gas Operator | Jan 1985 |
| 375 | Mapco Oil Company | | Oil & Gas Operator | Jan 1985 |
| 376 | Mapco Production Co | Billings, MT 59102 | Oil & Gas Operator | Apr 1994 |
| 377 | Maple Energy Holdings, LLC | Houston, TX 77007 | Oil & Gas Operator | Sep 2023 |
| 378 | Maple Grove Enterprises Inc | Rimersburg, PA 16248-6415 | Oil & Gas Operator | Dec 2025 |
| 379 | Maple Gulf Coast Props. Corp. | | Oil & Gas Operator | Jun 1989 |
| 380 | Maple Lane Farms Dairy And Grain LLC | Marietta, NY 13110 | Gas Operator | Dec 2024 |
| 381 | Maple Leaf Energ | | Oil & Gas Operator | Sep 1989 |
| 382 | Maple Properties Corp | Dallas, TX 75204 | Oil & Gas Operator | Jan 1999 |
| 383 | Mar Oil & Gas Corp. | Santa Fe, NM 87502 | Oil & Gas Operator | Apr 2026 |
| 384 | Mar Oil Company | Upper Sandusky, OH 43351 | Oil & Gas Operator | Dec 2023 |
| 385 | Mar-Bar Enterprises Inc | Cushing, OK 74023-3031 | Oil Operator | Feb 2026 |
| 386 | Mar-Bec Energy Company, L.L.C. | Shreveport, LA 71105 | Oil & Gas Operator | May 2001 |
| 387 | Mar-Lou Oil Co., LLC | Wilson, KS 67490 | Oil Operator | Feb 2026 |
| 388 | Mar-Low Corporation | | Oil & Gas Operator | Mar 1992 |
| 389 | Mar-Win Development Co. | | Oil & Gas Operator | Nov 1988 |
| 390 | Mar/Reg Investments | Irving, TX 75016 | Oil & Gas Operator | Jul 1999 |
| 391 | Mar/Reg Oil Company | Reno, NV 89511 | Oil & Gas Operator | Mar 2026 |
| 392 | Maralex Resources Inc | Ignacio, CO 81137 | Oil & Gas Operator | Mar 2026 |
| 393 | Maralo, Inc. | Midland, TX 79702 | Oil & Gas Operator | Dec 1998 |
| 394 | Maralo, LLC | Midland, TX 79702 | Oil & Gas Operator | Mar 2008 |
| 395 | Maram Energy Inc | MT Vernon, OH 43050 | Oil & Gas Operator | Dec 2025 |
| 396 | Maran Oil Company | San Antonio, TX 78216 | Oil & Gas Operator | Dec 2020 |
| 397 | Maran Oil Company, LLC | San Antonio, TX 78216 | Oil & Gas Operator | Mar 2022 |
| 398 | Maranatha Energy Corporation | Athens, WV 24712 | Oil & Gas Operator | Dec 2021 |
| 399 | Maranatha Exploration Inc | Killbuck, OH 44637 | Oil & Gas Operator | Dec 1992 |
| 400 | Maranatha Exploration, LP | Wichita Falls, TX 76307 | Oil Operator | Feb 2012 |