| 1 | M & R Exploration Company | Houston, TX 77074 | Oil & Gas Operator | Aug 2003 |
| 2 | M. J. G., Inc. | Alice, TX 78333 | Oil & Gas Operator | Jul 2010 |
| 3 | Magnum Producing & Operating Co. | Corpus Chrsti, TX 78471 | Oil & Gas Operator | Jan 2004 |
| 4 | Magnum Producing, LP | Corpus Chrsti, TX 78401 | Oil & Gas Operator | Dec 2025 |
| 5 | Magruder, Edwin H., Jr. | Midland, TX 79701 | Oil & Gas Operator | Oct 2019 |
| 6 | Maguire Oil Company | Dallas, TX 75270 | Oil & Gas Operator | Mar 2015 |
| 7 | Main Energy, Inc. | Houston, TX 77079 | Oil & Gas Operator | May 2009 |
| 8 | Maralo, Inc. | Midland, TX 79702 | Oil & Gas Operator | Dec 1998 |
| 9 | Marathon Oil Company | Houston, TX 77252 | Oil & Gas Operator | Oct 2025 |
| 10 | Marquee Corporation | Houston, TX 77024 | Oil & Gas Operator | Dec 2025 |
| 11 | Marshall Petroleum, Inc. | Houston, TX 77040 | Oil & Gas Operator | Aug 2003 |
| 12 | Marshall, A. B. | Houston, TX 77050 | Oil & Gas Operator | Sep 1995 |
| 13 | Marwell Petroleum LTD Partnrship | Houston, TX 77027 | Oil & Gas Operator | Dec 2025 |
| 14 | Marwell Petroleum, Inc. | Houston, TX 77057 | Oil & Gas Operator | Apr 2006 |
| 15 | Maverick Oil Company LLC | Pasadena, TX 77505 | Oil Operator | Dec 2025 |
| 16 | Maxim Energy Corporation | Baytown, TX 77520 | Oil & Gas Operator | Aug 2025 |
| 17 | MBX Operating LLC | Houston, TX 77007 | Oil & Gas Operator | Dec 2025 |
| 18 | McCarter, A. Nelson | Houston, TX 77063 | Oil & Gas Operator | Aug 2003 |
| 19 | McDay Energy Corp. | Dallas, TX 75206 | Oil & Gas Operator | Dec 2025 |
| 20 | McDonald Production | Lubbock, TX 79408 | Oil & Gas Operator | Mar 2003 |
| 21 | McLeod, George L. Inc. | Houston, TX 77079 | Oil & Gas Operator | Sep 2002 |
| 22 | McRae Exploration & Prod., Inc. | Houston, TX 77064 | Oil & Gas Operator | Feb 2017 |
| 23 | Medallion Production Company | Tulsa, OK 74103 | Oil & Gas Operator | May 1997 |
| 24 | Memorial Exploration Company | Saint Louis, MO 63105 | Oil & Gas Operator | Aug 1996 |
| 25 | Merenco | Midland, TX 79702 | Oil & Gas Operator | Dec 1996 |
| 26 | Merit Energy Company | Dallas, TX 75240 | Oil & Gas Operator | Dec 2025 |
| 27 | Midpar L.P. | Midland, TX 79702 | Oil & Gas Operator | Feb 1995 |
| 28 | Milagro Exploration, LLC | Houston, TX 77010 | Oil & Gas Operator | Aug 2018 |
| 29 | Mission Resources Corporation | Houston, TX 77002 | Oil & Gas Operator | Mar 2008 |
| 30 | Mission River Systems, Inc. | Corpus Chrsti, TX 78473 | Oil & Gas Operator | Dec 2025 |
| 31 | Mitchell Energy Corp | Houston, TX 77002 | Oil & Gas Operator | Aug 2013 |
| 32 | MJ Oil, Inc. | Houston, TX 77265 | Oil & Gas Operator | Dec 2025 |
| 33 | Mobil Oil Corporation | Houston, TX 77210 | Oil & Gas Operator | Dec 2007 |
| 34 | Mobil Producing TX. & N.M. Inc. | Spring, TX 77389 | Oil & Gas Operator | Dec 2025 |
| 35 | Mojac Energy Corp. | Houston, TX 77056 | Oil & Gas Operator | Dec 1997 |
| 36 | Morgan Enterprises, Inc. | Houston, TX 77024 | Oil & Gas Operator | Dec 2025 |
| 37 | Mosbacher Energy Company | Houston, TX 77002 | Oil & Gas Operator | Dec 2025 |
| 38 | Moses, Tom | Beaumont, TX 77702 | Oil Operator | Dec 2025 |
| 39 | Mse Operating Corp. | Beaverton, OR 97008 | Oil & Gas Operator | Dec 2025 |
| 40 | MW Petroleum Corporation | Houston, TX 77056 | Oil & Gas Operator | Mar 2015 |