Cover art
Piper, H. Beam. Paratime. Ace 1981.

Piper, H. Beam. Paratime
Summary: A series of tales involving Verkan Vall and the Paratime Police, some more explicitly than others. Allohistorical content is weak except in "He Walked around the Horses" and Lord Kalvan of Otherwhen. The infinite parallel Earths of Paratime are classed in five "levels" dependent on the success of the purported colonization of Earth by humanity (which arose on Mars) approximately 75 thousand years ago. Our timeline is classed as Fourth Level since colonization barely succeeded but all memory of it has been lost. The Paratime Police arose in the First Level, in which colonization was highly successful.
Series note: Related stories either collected in Paratime! or assembled into Lord Kalvan of Otherwhen. The contents of those two books have been collected in the omnibus volume The Complete Paratime. A novel expansion of the short story "Time Crime" as by Piper and John F. Carr has also been published, and Carr has announced the plans for two sequels, Time Troubles and Time Wars.

Piper, H. Beam. Paratime!
Summary: Collection of "He Walked Around the Horses", "Police Operation", "Last Enemy", "Temple Trouble", and the original "Time Crime". But except for "He Walked Around the Horses", the parallel Earths described are mostly exotic locales and none have a recent and/or clear divergence from ours.
Comments: Copyright page states that the book title is Paratime! but the cover and title page omit the exclamation mark.
Published: Ace 1981 (0441651690BUY), 1983 (0441651704BUY), and 1986 (0441651712BUY).
Published: Included in The Complete Paratime, Ace 2001 (0441008011BUY).

Piper, H. Beam. "He Walked Around the Horses"
Divergence: 1777 CE
What if: Burgoyne won at Saratoga, forestalling American independence and the Age of Revolution.
Summary: In 1809, Germans investigate a man claiming to be a British diplomat and carrying documents regarding some fantastical French emperor named Napoleon.
Series note: A Paratime story.
Comments: The inclusion of this as a Paratime story is indirectly explained in "Police Operation", q.v.
Published: In Astounding, April 1948; World of Wonder (ed. Fletcher Pratt), Twayne 1951; Best SF 3 (ed. Edmund Crispin), Faber 1958, 1963, SFBC 1960; Aspects of Science Fiction (ed. Geoff Doherty), Billings 1959, J. Murray 1963, and Billings 1970 (0719522153); Science Fiction Through the Ages 2 (ed. I.O. Evans), Panther 1966; A Science Fiction Argosy (ed. Damon Knight), Simon & Schuster 1972 (0671211269), SFBC 1972; Space Mail (eds. Isaac Asimov, Martin H. Greenberg and Joseph Olander), Fawcett 1980; Paratime!, q.v.; Isaac Asimov's Science Fiction Treasury (eds. Isaac Asimov, Martin H. Greenberg and Joseph Olander), Bonanza 1980 (0517336359); The Golden Age of Science Fiction (ed. Kingsley Amis), Hutchinson 1981; Penguin 1983; Isaac Asimov Presents the Great SF Stories: 10 (1948) (eds. Isaac Asimov and Martin H. Greenberg), DAW 1983; Alternative Histories: Eleven Stories of the World as It Might Have Been (eds. Charles G. Waugh and Martin H. Greenberg), q.v.; and The Amis Story Anthology: A Personal Choice of Short Stories (ed. Kingsley Amis), Hutchinson 1992 (0099659506).
Original in: English.
Translation: French by Alain Rague as "L'Homme qui apparut", in Histoire de la 4ègme dimension (ed. [[editor unknown]]), Livre de Poche 1986 (2253032956).
Translation: German by Eva Malsch as "Er ging um die Pferde herum", in Sternenpost 3 (eds. Isaac Asimov, Martin H. Greenberg, and Joseph H. Olander), Möwig 1984 (3811867350).
Translation: German by Lore Strassl as "Der Mann, der um die Pferde herumging", in Schöne verkehrte Welt: Phantastische Geschichten zur Geschichte (ed. René Oth), q.v.
Translation: Italian by Bruno Fonzi as "Passò intorno ai cavalli", in Le Meraviglie del possibile. Antologia della fantascienza (eds. Sergio Solmi e Carlo Fruttero), Einaudi 1959; Le Meraviglie del possibile. Antologia della fantascienza 1 (eds. Sergio Solmi e Carlo Fruttero), Einaudi 1992 (8806129341).
Translation: Italian by Giampaolo Cossato and Sandro Sandrelli as "Camminò intorno ai cavalli", in Le grandi storie della fantascienza 10 (eds. Isaac Asimov and Martin H. Greenberg), S.I.A.D. 1984, Bompiani 1993 (8845220532).

Piper, H. Beam. "Police Operation"
Summary: Paracop Verkan Vall searches for an anomalous Venusian nighthound loose on Fourth-Level Earth.
Series note: A Paratime story.
Published: In Astounding, July 1948; Space Police (eds. Andre Norton), Cleveland 1956; The Best of Astounding (ed. Tony Lewis), Baronet 1978 (0894370243); Paratime!, q.v.; and Analog: The Best of Science Fiction (ed. anon.), A&W/Galahad 1985 (088365637X).
Original in: English.
Translation: German by Dolf Strasser as "Der venusische Wuerger", in SF-Stories 66 (ed. Walter Spiegl), Ullstein 1977 (3548033237).

Piper, H. Beam. "Last Enemy"
Summary: Verkan Vall bails out a psychic researcher on a Second-Level timeline where reincarnation is a proven fact.
Series note: A Paratime story.
Published: In Astounding, August 1950; Astounding SF Anthology (ed. John W. Campbell), Simon & Schuster 1952; Paratime!, q.v.; and Robert Adams' Book of Alternate Worlds, q.v. (eds. Robert Adams, Martin H. Greenberg, and Pamela Crippen Adams).
Original in: English.
Translation: French by Pierre Billon as "Le dernier ennemi", in Fiction, Special #6, Opta 1966.

Piper, H. Beam. "Temple Trouble"
Summary: Verkan Vall assists a paratime substation disguised as a temple.
Series note: A Paratime story.
Published: In Astounding, April 1951 and Paratime!, q.v.
Original in: English.
Translation: German by Bodo Baumann as "Machtkampf der Goetzen", in SF-Stories 5 (ed. Walter Spiegl), Ullstein 1970 (3548028047).
Translation: German by Lore Strassl as "Tempelschwierigkeiten", in Das Zeitverbrechen, Pabel 1984 (3811850148).

Cover art
Piper, H. Beam, and John F. Carr. Time Crime. Pequod 2010.

Piper, H. Beam, and John F. Carr. Time Crime
Summary: Verkan Vall breaks up a crosstime slave ring.
Series note: A Paratime story.
Published: Pequod 2010 (0937912085BUY).
Published: Expanded from a novella by Piper in Astounding, February-March 1955 and Paratime!, q.v.
Original in: English.
Translation: German of the original story by Bodo Baumann as "Sklaven der Zeit", in SF-Stories 6 (ed. Walter Spiegl), Ullstein 1971 (3548028187).
Translation: German of the original story by Lore Strassl as "Das Zeitverbrechen", in Das Zeitverbrechen, Pabel 1984 (3811850148).

Cover art
Piper, H. Beam. Lord Kalvan of Otherwhen. Ace 1984 (cover art by Michael Whelan).

Piper, H. Beam. Lord Kalvan of Otherwhen [vt Gunpowder God]
Divergence: c 2000 BCE
What if: Bronze Age Indo-Aryans crossed the Bering Strait to colonize the Americas.
Summary: A Pennsylvania state trooper is transported to a North America where priests of Styphon exert political control over a network of feudal kingdoms through their monopoly on gunpowder.
Series note: The only Lord Kalvan tale and full-length novel in the Paratime series written by Piper. Several novel-length Lord Kalvan sequels have been written by John F. Carr and Roland J. Green. They are Carr and Green's Great Kings' War, Carr's Kalvan Kingmaker, Carr's Siege at Tarr-Hostigos, and Carr's The Fireseed Wars, all q.v. A related gaming supplement by Mike Gilbert titled Down Styphon! A Musket and Pike War Game Based on Lord Kalvan of Otherwhen was published by Fantasy Games Unlimited in 1977.
Published: As Lord Kalvan of Otherwhen, Ace 1965, 1977 (0441490514), 1981 (0441490530), 1984 (0441490557BUY); Garland 1975 (082401420X).
Published: As Gunpowder God, Sphere 1978 (0722168772).
Published: Included in The Complete Paratime, Ace 2001 (0441008011BUY).
Published: Fix-up of 1) "Gunpowder God", in Analog, November 1964; Time Wars (eds. Charles G. Waugh and Martin H. Greenberg), Tor 1986 (0812530489, 0812530497), The Good Old Stuff (ed. Gardner Dozois), Griffin 1998 (0312192754); and 2) "Down Styphon", in Analog, November 1965; Robert Adams' Book of Soldiers (eds. Robert Adams, Pamela Crippen Adams and Martin H. Greenberg), Signet 1988 (0451155599).
Original in: English.
Translation: French by Michel Deutsch as Kalvan d'outre-temps, Opta 1972.
Translation: German by Helmut Bittner as Der Mann, der die Zeit betrog, Winther 1967.
Translation: Italian by Cesare Gavioli as Lord Kalvan di Altroquando, La Tribuna 1968.
Translation: Italian by Roberta Rambelli as Lord Kalvan d'Altroquando, Libra 1979.

Piper, H. Beam. The Complete Paratime
Series note: Omnibus volume including all of the stories from Paratime! and the novel Lord Kalvan of Otherwhen.
Published: Ace 2001 (0441008011BUY).