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- "Pants" = Clarence Rowland, United States baseball player
- "Pap" = Jonathan Papelbon, American closer
- "Pat the Bat" = Pat Burrell, American left fielder
- "Peanuts" = Mamie Johnson, American Negro League baseball player
- "Pee Wee" =
- Harold Reese, American shortstop
- Paul Wanninger, American baseball player
- "The Peerless Leader" = Frank Chance, American first baseman
- "The People's Cherce" = Dixie Walker, American right fielder
- "Penguin" = Ron Cey, American third baseman
- "Pepper" =
- Johnny Martin, American outfielder and third baseman
- Lavonne Paire Davis, female American baseball player
- "Perpetual Pedro" = Pedro Feliciano, Puerto Rican relief pitcher
- "Piper" = Lorenzo Davis, United States Negro League baseball player
- "Poosh 'em up" = Tony Lazzeri, United States baseball player
- "Pop" = John Henry Lloyd, United States baseball player
- "Pops" = Willie Stargell, United States baseball player
- "Popeye" = Don Zimmer, United States baseball player and manager
- "Preacher" = Elwin Roe, United States baseball player
- "El Presidente" = Dennis Martínez, Nicaraguan starting pitcher
- "Pronk" = Travis Hafner, United States baseball player
- "Psycho" = Steve Lyons, United States baseball player
- "Puddin' Head" = Willie Jones, United States baseball player
- "Pudge" =
- Carlton Fisk, American catcher
- Iván Rodríguez, Puerto Rican catcher
- "Pumpsie" = Elijah Green, American utility infielder
Read more about this topic: List Of Baseball Player Nicknames