Crossover

Due to the shared nature of the "Xenaverse," crossovers between principle characters of the three series frequently occurred and are sometimes hard to define.

Crossover episodes
Using a strict definition of appearances by the seven regulars (Hercules, Iolaus, Xena, Gabrielle, Young Hercules, Young Iolaus, Jason) in series other than their own, the following episodes are crossovers:
 * HTLJ
 * "Judgment Day"
 * "Twilight"
 * "Top God"
 * XWP
 * "Prometheus"
 * "The Quest"
 * "God Fearing Child"

The HTLJ episode "The Warrior Princess," which featured Xena, was developed before plans for a spin-off began. "The Gauntlet" and "Unchained Heart" were written to segway straight into Xena: Warrior Princess.

The HTLJ episode "Stranger in a Strange World" featured parallel universe versions of Xena and Gabrielle. Versions from an alternate timeline were also seen in "Armageddon Now: Part 2."

Lucy Lawless returned to HTLJ as the character of Lyla, while starring in her own show, for the episode "Outcast." Renee O'Connor also portrayed a modern-day character in the episode "For Those of You Just Joining Us." Ryan Gosling portrayed the character Zylus in the Young Hercules-inspired episode "The Academy."

Michael Hurst, during and after portraying Iolaus and Iolaus 2 on Hercules, appeared several times as other characters in the other series':
 * XWP
 * "Mortal Beloved" (Charon)
 * YH
 * Young Hercules (Jeweler)
 * "A Lady in Hades" (Charon)
 * XWP
 * "You Are There" (Nigel)

Crossover media
The animated movie, Hercules and Xena - The Animated Movie: The Battle for Mount Olympus was a feature length story with equal weight on both Hercules and Xena characters.

Other minor crossover media include:
 * The Marriage of Hercules and Xena
 * The Official Herc and Xena Yearbook
 * Hercules & Xena: Alliance of Heroes

Appearances by Characters
Other than the characters mentioned above, several appearances by minor characters from one show to the other occurred, some as crossovers, others simply to stress the nature of the shared continuity. Ares, for example, was equally a villain on Hercules, Xena, and Young Hercules.

Jason, while a main character on Young Hercules, was originally a recurring character with several appearances. This is a unique situation.

HTLJ characters
Characters who appeared on HTLJ first.
 * Alcmene
 * Young Hercules
 * 6 YH appearances
 * Aphrodite
 * 11 XWP appearances
 * Apollo
 * YH: "Ares on Trial"
 * YH: "Apollo"
 * Ares
 * 29 XWP appearances
 * Young Hercules
 * 16 YH appearances
 * Artemis
 * XWP: "Motherhood"
 * Athena
 * YH: "Ares on Trial"
 * XWP: "Amphipolis Under Siege"
 * XWP: "Looking Death in the Eye"
 * XWP: "Motherhood"
 * Autolycus
 * 8 XWP appearances
 * Castor
 * YH: "Winner Take All"
 * YH: "A Lady in Hades"
 * YH: "Dad Always Liked Me Best"
 * Charon
 * XWP: "Mortal Beloved"
 * YH: "A Lady in Hades"
 * XWP: "You Are There"
 * Cupid
 * XWP: "For Him the Bell Tolls"
 * XWP: "A Comedy of Eros"
 * Falafel
 * XWP: "Lyre, Lyre, Hearts on Fire"
 * Cheiron
 * Young Hercules
 * 25 YH appearances
 * Deimos
 * XWP: "Motherhood"
 * Erytheia
 * YH: "Parent's Day"
 * Hades
 * 7 XWP appearances
 * YH: "A Lady in Hades"
 * Hephaestus
 * 6 YH appearances
 * XWP: "Looking Death in the Eye"
 * XWP: "Motherhood"
 * Hera
 * YH: "Down and Out in Academy Hills"
 * YH: "Herc's Nemesis"
 * XWP: "God Fearing Child"
 * Leda
 * YH: "Dad Always Liked Me Best"
 * Menelaus
 * XWP: "Beware Greeks Bearing Gifts"
 * Michael
 * 5 XWP appearances
 * Nemesis
 * YH: "Herc's Nemesis"
 * Odin
 * XWP: "The Ring"
 * XWP: "The Rheingold"
 * XWP: "Return of the Valkyrie"
 * XWP: "You Are There"
 * Pankos
 * XWP: "Fallen Angel"
 * Prometheus
 * XWP: "Prometheus"
 * Salmoneus
 * XWP: "The Black Wolf"
 * XWP: "The Greater Good"
 * XWP: "Here She Comes... Miss Amphipolis"
 * Strife
 * 18 YH appearances
 * Zeus
 * YH: "Valley of the Shadow"
 * XWP: "God Fearing Child"

XWP characters
Characters who appeared on XWP first.
 * Atropos
 * HTLJ: "Judgment Day"
 * Bacchus
 * YH: "Lure of the Lyre"
 * YH: "Fame"
 * YH: "Lyre, Liar"
 * Julius Caesar
 * HTLJ: "Render Unto Caesar"
 * Callisto
 * HTLJ: "Surprise"
 * HTLJ: "Armageddon Now: Part 1"
 * HTLJ: "Armageddon Now: Part 2"
 * Celesta
 * HTLJ: "Regrets, I've Had a Few"
 * Discord
 * 7 HTLJ appearances
 * Young Hercules
 * 8 YH appearances
 * Ephiny
 * HTLJ: "Prodigal Sister"
 * HTLJ: "Sky High"
 * Hope
 * HTLJ: "Armageddon Now: Part 1"
 * HTLJ: "Armageddon Now: Part 2"
 * Joxer
 * HTLJ: "When a Man Loves a Woman"
 * Karis
 * HTLJ: "Highway to Hades"
 * Orpheus
 * YH: "Lure of the Lyre"
 * YH: "Fame"
 * YH: "Lyre, Liar"
 * Penelope
 * YH: "Cyrano de Hercules"
 * Sisyphus
 * HTLJ: "Highway to Hades"
 * Robert Tapert
 * HTLJ: "Yes, Virginia, There is a Hercules"
 * HTLJ: "For Those of You Just Joining Us"
 * Xenan
 * HTLJ: "Prodigal Sister"

YH characters
Characters who appeared on YH first.
 * Lilith
 * HTLJ: "The Academy"
 * HTLJ: "A Wicked Good Time"