Executive Leadership

Ms. Mannen is Chairman, President and Chief Executive Officer of MPLX GP LLC. She is also Chairman, President and Chief Executive Officer of Marathon Petroleum Corporation.

Ms. Mannen was named Chairman in 2026. She was named President of Marathon Petroleum Corporation in January 2024 and Chief Executive Officer in August 2024. Previously, she served as Executive Vice President and Chief Financial Officer of Marathon Petroleum Corporation since 2021.

Prior to joining Marathon Petroleum Corporation in 2021, Ms. Mannen served as Executive Vice President and Chief Financial Officer of TechnipFMC, a leading global engineering services and energy technology company incorporated in the United Kingdom and headquartered in Paris and Houston. From 2011 to 2017, she was Chief Financial Officer at FMC Technologies, prior to its merger with Technip SA, which Ms. Mannen played a key role in negotiating and executing. Before that, she served as the company's Deputy Chief Financial Officer and Treasurer from 2010 to 2011 and Vice President of Administration from 2007 to 2010. Prior to joining FMC Technologies in 1986, Ms. Mannen was Finance Manager for Sheller-Globe Corporation.

Ms. Mannen holds a bachelor's degree in accounting and a Master of Business Administration degree from Rider University.

Ms. Mannen serves as Chairman of the American Petroleum Institute (API), on the executive committee of American Fuel and Petrochemical Manufacturers (AFPM) and the executive committee of the Ohio Business Roundtable, and is a member of The Business Council. Ms. Mannen is a member of the Prudential Financial board of directors, where she serves on the board’s corporate governance and business ethics committee and compensation and human capital committee. She also serves as Secretary of the Cynthia Woods Mitchell Pavilion board of directors and is a member of its executive and finance committees. Ms. Mannen previously served on the board of directors of Owens Corning.

Mr. Hagedorn is executive vice president and chief financial officer – MPLX.

Mr. Hagedorn joined MPLX GP LLC in 2017 as vice president and controller. In 2021, he was named senior vice president and controller of Marathon Petroleum Corporation. Prior to joining MPLX GP LLC, Mr. Hagedorn was vice president and controller at CONSOL Energy Inc. He was a key member of the leadership team that prepared for the formation and initial public offering of a midstream master limited partnership formed by CONSOL Energy and served as the partnership's chief accounting officer. Mr. Hagedorn joined CONSOL in 2012 as director, financial accounting and was named assistant controller in 2014, and vice president and controller in 2015. He served as chief accounting officer for CONE Midstream Partners LP from 2014 to 2015. Mr. Hagedorn joined PricewaterhouseCoopers in 1998. During his 14-year career with PwC, he held the positions of audit associate, audit senior associate, audit manager and audit senior manager. Mr. Hagedorn assumed his current position in 2024.

Mr. Hagedorn earned a bachelor’s degree in accounting from West Virginia University. He is a licensed certified public accountant in Pennsylvania.

Mr. Hagedorn serves on the board of directors of MPLX GP LLC.

Mr. Floerke is executive vice president and chief operating officer – MPLX.  

Mr. Floerke joined MPLX in 2015, at the time of the MPLX and MarkWest combination. He joined MarkWest in 2013 as senior vice president, Northeast region. He was named executive vice president and chief commercial officer in 2015 and named executive vice president, gathering and processing in 2016. In 2020, Mr. Floerke was named chief operating officer and executive vice president, Gathering & Processing, Trucks & Rail and assumed his current position in 2021. Prior to joining MarkWest, Mr. Floerke served as vice president, Eastern region for Access Midstream Partners. He has a broad background spanning multiple disciplines and industries for more than 25 years, including senior management roles at Williams, where he began his career, as well as MasTec, Alberici, One Communications, and Chesapeake Midstream.

Mr. Floerke graduated from the Colorado School of Mines with a bachelor’s degree in petroleum engineering. He is a graduate of the Program for Management Development at Harvard Business School.

Mr. Floerke serves on the board of directors of TransTech Group, LLC.

Mr. Lyon is senior vice president Logistics & Storage – MPLX. 

Mr. Lyon joined Marathon Petroleum Corporation (MPC) in 1989 as an engineer in Indianapolis, Indiana. While in Indianapolis, he worked in various positions in the midstream and engineering organizations. In 2002, Mr. Lyon transferred to Findlay, Ohio, where he has held a variety of leadership positions. He was named product quality manager in 2005 and operations manager for Marathon Pipe Line LLC (MPL), a wholly owned subsidiary of MPLX, in 2006. Mr. Lyon was named district manager in Transport and Rail for the Terminal, Transport and Marine business in 2008 and manager, Marketing and Transportation Engineering for MPC in 2010. He was named vice president of operations for MPL in 2011. In 2018, Mr. Lyon was named vice president, operations of MPLX GP LLC and president of MPL. He assumed his current position in 2022.

Mr. Lyon graduated from Purdue University with a Bachelor of Science degree in construction engineering in 1989. He was licensed as a Professional Engineer in 1994.   

Mr. Lyon, by appointment of the U.S. Secretary of Transportation, Elaine Chao, served on the liquid pipeline advisory committee from 2019 to 2025. He serves on the board of the Liquid Energy Pipeline Association (LEPA) and served as the chair on the board in 2023; and he serves as chair of the board of the Louisiana Offshore Oil Port (LOOP). Mr. Lyon is a member of the American Petroleum Institute’s (API) Midstream Committee, and served as past member of API’s pipeline subcommittee steering group, of which he served as chair in 2020; the API-LEPA pipeline safety excellence steering committee; and the LEPA Federal Energy Regulatory Commission (FERC) policy committee. He co-chaired the public engagement recommended practice development group (API RP 1185), which included industry, public and government entities for the entire pipeline segment. Mr. Lyon also served as chair of the pipeline industry’s implementation of the Pipeline Safety Management System (API RP 1173) from 2015-2018 and on the Michigan Pipeline Safety Advisory Board, by appointment of Governor Rick Snyder, from 2017-2018.

Mr. Lyon has actively worked to foster a culture of safety within MPC and across the industry. In 2019, Mr. Lyon received the Pipeline Leadership Award for driving transformation and improvement in the industry. In 2019 and 2023, MPL was awarded the API Distinguished Pipeline Safety Award. Selected by pipeline industry peers, the award acknowledged MPL for fostering a culture of safety, sharing and implementing best practices, and actively participating in and contributing to API policy and technical work. In 2024, MPL received the President’s Award from the Common Ground Alliance for its exceptional dedication to damage prevention. Also in 2024, Mr. Lyon accepted on behalf of MPC the Texas Salutes the Coast Guard Award from the Coast Guard Foundation, recognizing the company’s leadership in safe maritime operations and community support. In 2025, the International Liquid Terminals Association recognized the Logistics & Storage Terminals organization with the Platinum Safety Award for its exemplary safety culture and focus on safe operations.

Ms. Benson is chief legal officer and corporate secretary of MPLX GP LLC. She is also chief legal officer and corporate secretary of Marathon Petroleum Corporation.

Ms. Benson began her career with Marathon as a tax attorney in 1998.

She was named Government Affairs manager in 2001 and joined the Law organization as an operations attorney in 2003. Ms. Benson was promoted to senior attorney, downstream business in 2006 and to group counsel, North American production for Marathon Oil Company in Houston in 2010. Ms. Benson was named Marathon Petroleum Corporation group counsel, Law ‐ Corporate and Finance in 2011 and assistant general counsel, Law ‐ Corporate and Finance in 2012. In 2016, she was appointed as vice president, chief securities, governance & compliance officer and corporate secretary. She assumed her current position in 2024.

Ms. Benson graduated from The Ohio State University in 1987 with a bachelor’s degree in political science and a Juris Doctor degree from the University of Toledo College of Law in 1997. She completed the Executive Development Program at Northwestern University’s Kellogg School of Management in 2014.

Mr. Henschen is senior vice president of MPLX GP LLC. He is also executive vice president Refining of Marathon Petroleum Corporation. 

Mr. Henschen joined Marathon Petroleum in 2004 as a refining planner in Detroit, Michigan, and held many leadership positions with increasing responsibility in refining, maintenance, turnarounds and project management. In 2011, he was named the maintenance manager for the Detroit refinery and then became the maintenance manager for Marathon Petroleum’s Galveston Bay refinery. In 2017, Mr. Henschen was appointed director of reliability and engineering for Marathon Petroleum’s refining organization. He served in that role until 2020, when he was named vice president and general manager of the Garyville refinery. In 2024, Mr. Henschen was named senior vice president of refining operations. He assumed his current position in 2025.

Mr. Henschen served five years in the U.S. Army as a non-commissioned officer. During his service, he led teams in Germany, Iraq and Kuwait.

Mr. Henschen serves on the executive board of directors for the Louisiana Mid-Continent Oil and Gas Association (LMOGA). He also served as a member of the board of directors for the Greater Baton Rouge Industrial Alliance (GBRIA) and American Petroleum Institute (API).

Mr. Heppner is senior vice president of MPLX GP LLC. He is also chief strategy officer and senior vice president Business Development of Marathon Petroleum Corporation.

Mr. Heppner joined Marathon in 1988, where he held a variety of positions of increasing responsibility, including design engineer, construction engineer and project manager. In 1995, Mr. Heppner transferred to Emro Marketing Company, the predecessor of Speedway LLC, where he held various positions including purchasing and commercial services manager; business development manager; director of engineering services; and vice president of operations. In 2010, he was appointed director, wholesale marketing at MPC. In 2014, Mr. Heppner was appointed vice president of transition at Speedway. He was later named senior vice president of engineering services and corporate support at Speedway. He was named vice president, Commercial and Business Development for MPC in 2018 and senior vice president, Strategy and Business Development in 2021. He was named senior vice president of MPLX in 2022 and assumed his current position for MPC in 2024.

Mr. Heppner graduated from Ohio Northern University in 1988 with a Bachelor of Science degree in electrical engineering. He is a registered professional engineer in the state of Illinois. Mr. Heppner attended the Wharton School Advanced Management Program in 2013.

Mr. Heppner serves on the Board of Trustees at Ohio Northern University, as well as the board for Habitat for Humanity. He recently served as president of the United Way of Clark, Champaign and Madison Counties board of trustees, vice president of membership for the Boy Scouts of America, Black Swamp Council and was the campaign chairman for the Clark County March of Dimes. Mr. Heppner is a past member of the Children’s Miracle Network’s Board of Governors and Dayton Children’s Hospital Foundation board of trustees, as well as a past member of Wright State University College of Engineering and Computer Science External Advisory Board.

Mr. Hessling is senior vice president of MPLX GP LLC. He is also chief commercial officer of Marathon Petroleum Corporation.

Mr. Hessling began his career with Marathon in 1990 and served in a variety of Marketing positions in the Midwest. In 1994, he was named acquisition specialist and jobber marketing representative in Michigan, which led to him being named a sales manager. Mr. Hessling relocated to MPC’s Findlay, Ohio, office in 2000 where he was named Midwest exchange negotiator and domestic spot crude oil trader in 2001. In 2002, he was named Marketing coordinating manager and distillate pricing manager in 2004. In 2005, Mr. Hessling was named brand southern district manager in Atlanta. He returned to Findlay in 2011 as crude oil and logistics analysis manager. Mr. Hessling was appointed manager, crude oil and natural gas supply and trading manager in 2014.  He was named senior vice president, Crude Oil Supply and Logistics in 2018 and senior vice president, Global Feedstocks in 2021. He assumed his current position in 2024.

Mr. Hessling graduated with a bachelor’s degree in production management and marketing from Central Michigan University. He attended the Oxford Institute for Energy Studies in 2012.

Mr. Partee is senior vice president of MPLX GP LLC. He is also chief global optimization officer of Marathon Petroleum Corporation.  

Mr. Partee joined Marathon in 1995 as an accountant in Marathon Pipe Line. He progressed through positions of increasing responsibility before being named territory manager in the Wholesale Marketing southern region in 2004, district sales manager in 2006 and coordinating manager in 2008. In 2009, Mr. Partee was named commercial director for Speedway. In 2012, he was named vice president, Business Development and Franchise at Speedway. He served as MPC's manager of crude oil logistics and analysis beginning in 2014 and was named director of Business Development in 2017. He was named vice president, Business Development in February 2018 and senior vice president, Marketing in October 2018. In 2021, he was named senior vice president, Global Clean Products and assumed his current position in 2024.

Mr. Partee holds a bachelor’s degree in accounting from Bowling Green State University and an MBA from the University of Findlay. He is a past attendee of the Oxford Institute for Energy Studies.

Mr. Partee is a member of the American Petroleum Institute, where he previously served on the marketing subcommittee. Mr. Partee serves on the board of trustees at the University of Findlay.