- MacK, Connie Jr
- Madden, Martin G
- Mader, Dan
- Madigan, Lisa
- Madigan, Michael
- Mahoney, Tim
- Maldonado, Abel
- Maliki, Nouri
- Malone, David
- Malone, Jack
- Maloney, Carolyn B.
- Mandel, Adrienne A
- Mandel, Marvin
- Mandela, Nelson
- Manning, Pat
- Marcellino, Carl L
- March, Steve
- Margett, Bob
- Markey, Edward J
- Markowitz, Marty
- Marriott, Salima S
- Martin, Jim
- Martin, John L
- Martinez, Mel
- Mason, William
- Masters, Thomas
- Matheson, Jim
- Matthews, Gary
- Maxwell, W Henry
- May, Bob
- May, Karen
- Mayer, Robert
- Mayfield, Stan
- Mayo, John
- McCabe, Christopher J
- McCain, John
- McCall, Tom
- McCarthy, Carolyn
- McClintock, Tom
- McCollum, Bill
- McConnell, Mitch
- McCoy, Matt
- McCreary, Bill
- McCrery, Jim
- McDermott, Jim
- McDermott, Joe
- McDonald, Dan
- McDonnell, Bob
- McFadden, Nathaniel J
- McGuire, Jack
- McHale, Brian K
- McInnis, Scott
- McIntosh, Maggie L
- McIntyre, Mike
- McKee, Robert A
- McKeon, Larry
- McKinley, William
- McKinney, John
- Medvedev, Dmitry
- Meehan, Martin T
- Meek, Kendrick B.
- Menendez, Jose
- Menendez, Robert
- Menes, Pauline H
- Merkel, Angela
- Merkley, Jeff
- Meyer, Dan
- Meyer, Kevin
- Meyer, Mark
- Meyer, Tom
- Mica, John L
- Middleton, Thomas M
- Migden, Carole
- Mikulski, Barbara
- Millender-McDonald, Juanita
- Miller, Brad
- Miller, Carl
- Miller, Charles
- Miller, Dan
- Miller, David
- Miller, Doug
- Miller, Ed
- Miller, Frank
- Miller, Gary G
- Miller, George
- Miller, Jeff
- Miller, Ken
- Miller, Mark
- Miller, Paul
- Miller, Randy
- Miller, Sheila
- Miller, Thomas V. Mike
- Miller, Zell
- Mills, Howard D
- Mills, James
- Mitchell IV, Clarence M.
- Mitchell, Jerry
- Mitchell, Shawn
- Mitman, Phil
- Moe, Brian R
- Molina, Gloria
- Mondale, Walter
- Monroe, James
- Montgomery, Richard
- Montgomery, Velmanette
- Moody, Lisa
- Mooney, Alex X
- Moore, Dennis
- Moore, Garry
- Moore, Thomas
- Moran, James P
- Moran, Jerry
- Morella, Constance A
- Morgan, Carl
- Morgan, Harvey B.
- Morgan, Mike
- Morgan, Susan
- Morhaim, Dan K
- Morris, Greg
- Morris, Jeff
- Morris, Stephen
- Morrison, James
- Morrow, Bill
- Morton, Lorraine
- Moses, Mark
- Mubarak, Hosni
- Mugabe, Robert
- Mukasey, Michael
- Mulligan, Rosemary
- Munoz, Antonio
- Murkowski, Frank
- Murkowski, Lisa
- Murphy, Chris
- Murphy, Christopher
- Murphy, Donald E
- Murphy, Jim
- Murphy, Mary
- Murphy, Pat
- Murphy, Steve
- Murphy, Thomas
- Murphy, William H
- Murphy, William J
- Murray, Ed
- Murray, Kathleen
- Murray, Kevin
- Murray, Patty
- Murray, Therese
- Murtha, John P
- Musgrave, Marilyn
- Myers, David
- Myers, John
- Myung-bak, Lee