M
- Macfarlane, Robert Stetson (born 1899), NP 1951-1966.
- Mackenzie, William (1849–1923), TSR 1891-, CNoR 1895-, Brascan 1899-.
- MacMillan, Norman J. (1909–1978), CN 1967-1974.
- MacNamara, G. Allen, SOO 1950-1960.
- Magdei, Vasilie V. (d. 2006), Ulaanbaatar Railway 2004-2006.
- Mahone, William (1826–1895), N&P 1853-1858.
- Maidmen, Irving, NYSW.
- Mallory, Francis (1807–1860), N&P.
- Mann, Donald (1853–1934), CNoR.
- Manvel, Allen (b. 1837), ATSF 1889–1893.
- Markham, Charles H., IC 1911-1918.
- Marsh, Ernest S., ATSF 1958–1967.
- Marsh, Nathaniel, Erie 1861–1864.
- Marsh, Samuel, Erie 1859–1861 and four months in 1964.
- Matsuoka, Yōsuke (1880–1946), South Manchuria Railway 1935-1939.
- Maxwell, Gregory W., D&H 1970-1972.
- Maxwell, William, Erie 1842–1843.
- Maynard, Moses, Jr., LIRR 1851-1852.
- McAdoo, William G. (1863-1941), H&M 1902-1913; USRA 1917-18.
- McCabe, Frank Wells, D&H 1968.
- McCahey, James B., Jr. (1920–1998), CSS&SB.
- McCrea, James, PRR 1907–1912.
- McCreey, William, P&LE 1875-1877.
- McDonald, Angus Daniel (1878–1941), SP 1932–1941.
- McDonald, Morris (1865-1938), B&M 1913-1914, MEC 1914-1932.
- McGinnis, Patrick, B&M 1950-1960, NH 1954-.
- McIntyre, J. C., DME 1986-1996.
- McIver, Bruce C., LIRR 1985-1989.
- McKinnon, Arnold B., NS.
- McLean, David G. A., CN -present.
- McLeod, Archibald A., RDG.
- McNear, Denman, SP 1976-1979.
- McPherson, John D., IC, FEC 1999-2008.
- Mehdorn, Hartmut (born 1942), DB 1999–present.
- Mellen, Charles Sanger (1852–1927), NP 1897-1903, NH 1903-, MEC 1910-1914.
- Menk, Louis W., NP 1966-1970, BN.
- Mercier, Armand, SP 1941-1951.
- Merrick, Samuel V., PRR 1847–1849.
- Mięclewski, Maciej, PKP -2004.
- Miller, Dennis H., IAIS 2004–present
- Miller, E. Spencer (d. 2005), MEC 1952-1978.
- Millholland, James A., GC&C.
- Mitchell, Alexander (1817–1887), MILW 1864-1887.
- Mohan, D. M. "Mike", SP 1984-1996.
- Mohar, Mario, TFM -2005.
- Mohler, A. L., UP 1911-1916.
- Molson, John (1763–1836), C&StL.
- Moore, W. Gifford, L&HR 1968-.
- Moorman, Charles W. (b. 1953), NS 2004–present.
- Moran, Charles, Erie 1857–1859.
- Morrill, Anson P., MEC 1864-1866 and 1873-1875.
- Morris, William E., LIRR 1853-1862.
- Moyes, Chris (1949–2006), Go-Ahead Group 2005-2006.
- Moyers, Edward, SP -1995.
- Mudge, Henry U., RI 1909-1915.
- Murray, Leonard, SOO 1961-1978.
Read more about this topic: List Of Railroad Executives