- Mabry, John
- MacDougal, Mike
- Machado, Robert
- Macias, Jose
- Mack, Stacey
- Mack, Tom
- Mack, Tremain
- Mackey, John
- Macklin, David
- MacLean, John
- MacPhail, Lee
- Madden, John
- Maddox, Tommy
- Madison, Sam
- Madsen, Mark
- Maduro, Calvin
- Maese, Joe
- Maggert, Jeff
- Maggette, Corey
- Magloire, Jamaal
- Mahomes, Pat
- Mair, Adam
- Malakhov, Vladimir
- Malhotra, Manny
- Malik, Marek
- Malone, Karl
- Malone, Mike
- Maltbie, Roger
- Maltby, Kirk
- Mangini, Eric
- Mangum, Kris
- Mannelly, Patrick
- Manning Jr., Ricky
- Manning, Danieal
- Manning, Danny
- Manning, Eli
- Manning, Peyton
- Mantle, Mickey
- Manuel, Jerry
- Manumaleuna, Brandon
- Manzanillo, Josias
- Mapp, Justin
- Mara, Paul
- Mara, Tim
- Mara, Wellington
- Maranville, Rabbit
- Marbury, Stephon
- Marchant, Todd
- Marchetti, Gino
- Mare, Olindo
- Marichal, Juan
- Marion, Brock
- Marion, Shawn
- Markakis, Nick
- Markov, Andrei
- Markov, Danny
- Marleau, Patrick
- Marmol, Carlos
- Maroth, Mike
- Marquard, Rube
- Marquis, Jason
- Marrero, Eli
- Marsch, Jesse
- Marshall, Donyell
- Marshall, George Preston
- Marshall, Grant
- Marshall, James
- Marshall, Jim
- Marshall, Lemar
- Marshall, Sean
- Marte, Damaso
- Martin, Cecil
- Martin, Curtis
- Martin, David
- Martin, Doug
- Martin, Jacques
- Martin, Jamie
- Martin, Kenyon
- Martin, Mark
- Martin, Todd
- Martin, Tony
- Martinez, Antonio
- Martinez, Chris
- Martinez, Dave
- Martinez, Edgar
- Martinez, Pedro
- Martinez, Richard
- Martinez, Tino
- Martins, Steve
- Maryland, Russell
- Mashburn, Jamal
- Mason, Anthony
- Mason, Chris
- Mason, Derrick
- Mason, Desmond
- Mason, John
- Massenburg, Tony
- Masset, Nick
- Mastroeni, Pablo
- Mateo, Juan
- Mathews, Eddie
- Mathewson, Christy
- Mathis, Clint
- Mathis, Jeff
- Mathis, Terance
- Matsuzaka, Daisuke
- Matthew, Catriona
- Matthews, Bruce
- Matthews, Mike
- Matthews, Shane
- Mattiace, Len
- Mattingly, Don
- Maualuga, Rey
- Mawae, Kevin
- May, Brad
- Mayers, Jamal
- Mayes, Alonzo
- Mayfair, Billy
- Maynard, Brad
- Maynard, Don
- Mayne, Brent
- Mays, Joe
- Mays, Willie
- Mazeroski, Bill
- McAfee, Fred
- McAfee, George
- McAlister, Chris
- McAmmond, Dean
- McBride, Brian
- McBride, Trumaine
- McCabe, Bryan
- McCaffery, Ed
- McCardell, Keenan
- McCarron, Scott
- McCarthy, Joe
- McCarthy, Steve
- McCarty, Darren
- McCarty, David
- McCaskey, Michael
- McCleon, Dexter
- McCloud, Tyrus
- McClover, Darrell
- McClure, Todd
- McCord, Gary
- McCormack, Mike
- McCovey, Willie
- McCracken, Quinton
- McCrary, Michael
- McCree, Marlon
- McCullough, Andy
- McCullough, Mike
- McCumber, Mark
- McCutcheon, Daylon
- McDaniel, Ed
- McDaniel, Emmanuel
- McDaniel, Randall
- McDonald, Andy
- McDonald, Joan
- McDonald, Ken
- McDonald, Tommy
- McDuffie, O J
- McDuffie, O.J.
- McDyess, Antonio
- McElhenny, Hugh
- McEnroe, John
- McEwing, Joe
- McGahee, Willis
- McGann, Michelle
- McGee, Tony
- McGinest, Willie
- McGinnity, Joe
- McGlockton, Chester
- McGovern, Jim
- McGowan, Bill
- McGowan, Brandon
- McGrady, Tracy
- McGraw, John
- McGriff, Fred
- McGuire, Ryan
- McGwire, Mark
- McHale, Kevin
- McInnis, Jeff
- McIntosh, Chris
- McIntosh, Damion
- McKee, Jay
- McKenzie, Keith
- McKenzie, Mike
- McKie, Aaron
- McKie, Jason
- McKinney, Bill
- McKnight, James
- McKnight, Joe
- McLaren, Kyle
- McLaughlin, John
- McLemore, Mark
- McLeod, Kevin
- McMahon, Jim
- McMahon, Mike
- McMahon, Vince
- McMillon, Todd
- McNabb, Donovan
- McNair, Steve
- McNally, John
- McNamara, Rob
- McNeil, Ryan
- McNown, Cade
- McQuarters, R.W.
- Mecir, Jim
- Mediate, Rocco
- Medwick, Joe
- Meester, Brad
- Meier, Rob
- Meirelles, Fernando
- Meissner, Kimmis
- Melhuse, Adam
- Mendoza, Ramiro
- Menechino, Frank
- Meola, Tony
- Mercado, Hector
- Mercer, Ron
- Merloni, Lou
- Merritt, Ahmad
- Mesa, Jose
- Messier, Mark
- Metcalf, Eric
- Metcalf, Terrence
- Metropolit, Glen
- Meyer, Dave
- Meyer, Greg
- Meyer, Robert
- Meyer, Urban
- Mickelson, Phil
- Mickens, Ray
- Mielke, Mark
- Mientkiewicz, Doug
- Mihm, Chris
- Milburn, Glyn
- Miles, Darius
- Mili, Itula
- Miller, Aaron
- Miller, Allen
- Miller, Andre
- Miller, Arnold
- Miller, Bill
- Miller, Billy
- Miller, Brandon
- Miller, Bubba
- Miller, Cheryl
- Miller, Craig
- Miller, Damian
- Miller, Fred
- Miller, Jamir
- Miller, Jim
- Miller, John
- Miller, Johnny
- Miller, Josh
- Miller, Keith
- Miller, Kevin
- Miller, Mike
- Miller, Reggie
- Miller, Stephanie
- Miller, Travis
- Miller, Wade
- Milloy, Lawyer
- Mills, Chris
- Mills, Joanna
- Milton, Eric
- Minaya, Omar
- Mines, Fontel
- Minnis, Marvin
- Minor, Ryan
- Mirabelli, Doug
- Mirer, Rick
- Mironov, Boris
- Mitchell, Anthony
- Mitchell, Bobby
- Mitchell, Brian
- Mitchell, Donald
- Mitchell, Jeff
- Mitchell, Keith
- Mitchell, Kevin
- Mitchell, Pete
- Mitchell, Sam
- Mitchell, Scott
- Mitchell, Stephanie
- Mitchell, Willie
- Mix, Ron
- Mixon, Kenny
- Mize, Johnny
- Mize, Larry
- Mlicki, Dave
- Mobley, Cuttino
- Mobley, John
- Modano, Mike
- Modin, Fredrik
- Modry, Jaroslav
- Moeller, Chad
- Mohammed, Nazr
- Mohler, Mike
- Molina, Bengie
- Mondesi, Raul
- Montana, Joe
- Montgomery, Joe
- Montgomery, Monty
- Moody, Orville
- Moore, Charles
- Moore, Cliff
- Moore, Damon
- Moore, Dave
- Moore, Freddie
- Moore, Herman
- Moore, Jason
- Moore, Jessica
- Moore, Larry
- Moore, Mikki
- Moore, Pat
- Moore, Rob
- Moore, Ron
- Moore, Tom
- Mora, Melvin
- Moran, Sean
- Moreau, Ethan
- Moreno, Jaime
- Moreno, Juan
- Morey, Sean
- Morgan, Gil
- Morgan, Joe
- Morgan, John
- Morland IV, David
- Morris, Aric
- Morris, Derek
- Morris, Matt
- Morris, Sammy
- Morris, Terence
- Morrison, Bill
- Morrison, Brendan
- Morrow, Brenden
- Morse, John
- Morton, Brian
- Morton, Chad
- Morton, Johnnie
- Moses, J.J.
- Moss, Randy
- Mota, Guillermo
- Mottau, Mike
- Moulds, Eric
- Mourning, Alonzo
- Moya, Carlos
- Moyer, Jamie
- Mucha, Barb
- Muhammad, Muhsin
- Mulder, Mark
- Mulitalo, Edwin
- Mullan, Brian
- Muller, Kirk
- Mullin, Chris
- Mullins, Moon
- Munoz, Anthony
- Murcer, Bobby
- Murphy, Bob
- Murphy, Dick
- Murphy, Frank
- Murphy, Joe
- Murphy, Larry
- Murphy, Rob
- Murphy, Sean
- Murphy, Troy
- Murray, Eddie
- Murray, Tracy
- Murton, Matt
- Musial, Stan
- Mussina, Mike
- Mustain, Mitch
- Mutis, Jeff
- Mutombo, Dikembe
- Myers, Greg
- Myers, Jennifer
- Myers, Michael