P
- David Packard and William Hewlett — Hewlett-Packard
- František Palacký — Palacký University, Olomouc
- Paparazzo, a press photographer in Federico Fellini's film La Dolce Vita — paparazzi press photographers
- Vilfredo Pareto — Pareto principle, Pareto efficiency, Pareto distribution, Pareto index
- Bernard Parham — Parham Attack
- James Parkinson — Parkinson's disease
- Rosa Parks — Rosa Parks Highway
- Blaise Pascal — pascal — unit of pressure; Pascal's triangle, Pascal's Wager or Pascal's Gambit, Pascal programming language, Pascal's theorem
- Louis Pasteur — Pasteurization
- Wolfgang Pauli — Pauli exclusion principle
- Axel Paulsen — Axel, Figure skating jump
- Ivan Petrovich Pavlov — Pavlovian conditioning
- Anna Pavlova — Pavlova
- Giuseppe Peano — Peano axioms
- Jean Charles Athanase Peltier — Peltier effect
- William Penn — Pennsylvania
- James Cash Penney — J.C. Penney
- Roger Penrose — Penrose diagram, Penrose tiling, Penrose triangle, Penrose stairs, Penrose chickens
- Dom Pérignon (1638–1715), a blind French Benedictine monk — Dom Pérignon (wine)
- St. Peter — Saint-Pierre and Miquelon
- Alexander Petrov — Petrov's Defence
- Armand Peugeot - founder, Peugeot
- François-André Danican Philidor — Philidor Defence
- King Philip II of Spain — Philippines
- Gerard Philips — founder, Philips
- Joseph Pilates — the Pilates Method
- James Pimm - Pimm's
- Pinocchio - Pinocchio Syndrome
- Vasja Pirc — Pirc Defence
- William Pitt — Pittsburgh
- Max Planck — Planck's constant, Planck's law of black body radiation
- Henry Stanley Plummer — Plummer's disease
- Friedrich Carl Alwin Pockels — Pockels effect
- Joel Roberts Poinsett (1779–1851) — poinsettia
- Jean Louis Marie Poiseuille — poise — unit of viscosity, Poiseuille's Law
- Joseph Polchinski – Polchinski's paradox concerning free will and traversable wormholes
- Charles Ponzi (1877–1949) — Ponzi scheme, a kind of fraud
- Domenico Lorenzo Ponziani — Ponziani Opening
- Eugène Poubelle (1831–1907), French lawyer, administrator and diplomat — poubelle, French word for "dustbin"
- Pierre Poujade (1920–2003) — Poujadism
- Ferry Porsche — founder, Porsche
- Grigori Aleksandrovich Potemkin — Potemkin village
- Percivall Pott — Pott's disease, Pott's fracture
- Elvis Presley - Elvis impersonator
- Priapus - priapism
- Prince Edward, Duke of Kent and Strathearn - Prince Edward Island
- Procrustes — Procrustean bed
- William Procter and James Gamble — Procter & Gamble
- James Puckle inventor of The Defense Gun, better known as the Puckle gun
- Joseph Pulitzer — Pulitzer Prize
- Jan Evangelista Purkyně — Purkinje cell
- Pyrrhus of Epirus — Pyrrhic victory
- Pythagoras - Pythagorean theorem
Read more about this topic: List Of Eponyms (L-Z)