- Macy's – Rowland Hussey Macy
- Mahindra Group – K.C. Mahindra and J.C. Mahindra
- Maki – MimurA KenjI
- Malaguti – Antonio Malaguti
- Mamiya – Seichi Mamiya
- Manfrotto Group – Lino Manfrotto
- Mansory – Kourosh Mansory
- March Engineering – Initials of Max Mosley, Alan Rees, Graham Coaker, and Robin Herd
- Marchese – Carl Marchese
- Marconi Company – Guglielmo Marconi
- Marcus Marshall Motorsport – Marcus Marshall
- Mark Levinson – Mark Levinson
- Marks & Spencer – Michael Marks and Thomas Spencer
- Marriott Corporation (later split into Host Marriott and Marriott International) – J. Willard Marriott
- Mars, Incorporated – Frank C. Mars
- Marsh & McLennan Companies – Henry W. Marsh and Donald R. McLennan
- Marshall Amplification – Jim Marshall
- Martha Stewart Living Omnimedia – Martha Stewart
- Martini – Tico Martini
- Martini & Rossi – Alessandro Martini and Luigi Rossi
- Marzotto – Luigi Marzotto
- Matsushita Electric Industrial – Konosuke Matsushita
- Matrox – Branko MAtić and Lorne TROttier (and eXcellence)
- Mattel – Harold MATT Matson and ELliot Handler
- Mauser – Wilhelm and Paul Mauser
- Maybach – Wilhelm and Karl Maybach
- Maytag – F. L. Maytag
- Mazda – Jujiro Matsuda, also possibly inspired by Zoroastrian god Ahura Mazda.
- McAfee – John McAfee
- McCaw Cellular – Craig McCaw
- McDonald's – Richard and Maurice McDonald
- McDonnell Aircraft (to McDonnell Douglas) – James Smith McDonnell
- McGraw-Hill – John A. Hill and James H. McGraw
- McKesson Corporation – John McKesson
- McLaren – Bruce McLaren
- Meijer – Hendrik Meijer
- Mellon Financial Corporation – Thomas Mellon
- Menards – John Menard, Jr.
- Mercedes – named by Emil Jellinek for his daughter Mercédès Jellinek
- Merck – Friedrich Jacob Merck
- Merriam-Webster – George and Charles Merriam, and Noah Webster
- Merrill Lynch – Charles E. Merrill and Edmund C. Lynch
- Merzario – Arturo Merzario
- Messerschmitt – Willy Messerschmitt
- MGM or Metro-Goldwyn-Mayer – Samuel Goldfish, Edgar and Archibald Selwyn, and Louis B. Mayer
- Michael Waltrip Racing – Michael Waltrip
- Miele – Carl Miele
- Mikoyan – Artem Mikoyan
- MillenWorks – Rod Millen
- Minardi – Giancarlo Minardi
- Miramax Films – Max and Miriam Weinstein (parents of founders)
- Mitel – Michael Cowpland and Terry Matthews (MIke and TErry's Lawnmowers)
- Mitsuoka – Akio Mitsuoka
- Moët et Chandon – Claude Moët
- Molson – John Molson
- Momo – Giampiero Moretti (MOretti MOnza)
- Mondadori – Arnoldo Mondadori
- Montague Bikes – David Montague
- Monteverdi – Peter Monteverdi
- Moog Music – Dr. Robert Moog
- Morbidelli – Giancarlo Morbidelli
- Morgan Stanley – Henry S. Morgan and Harold Stanley
- Morgan Motor Company – H.F.S. Morgan
- Mosler Automotive – Warren Mosler
- Moto Guzzi – Carlo Guzzi
- Moto Morini – Alfonso Morini
- MV Agusta – Vincenzo and Domenico Agusta
- Myer - Sidney Myer
Read more about this topic: List Of Companies Named After People