All-Star Cast: The TV series. The question isn't finding characters voiced by known/famous actors, but finding characters who aren't. Look up a voice actor's list. It's just oozing with famous titles. It all came up to be because James Woods wanted to return and thus most of the original cast jumped along, and others got interested.
Likewise, unless you know your Greek mythology, the five Muses are Thalia (muse of Comedy and the plump one), Melpomene (muse of Tragedy and the one with the long, curly hair), Calliope (muse of Epic Poetry and the leader), Clio (muse of History and with the pony tail), and Terpsichore (muse of dance and choral poetry, the one in the two-piece toga).
Hey, It's That Voice!: Hades is James Woods; Phil is Danny DeVito; Hermes is Paul Shaffer, best known for being David Letterman's band leader on The Late Show with David Letterman (though Shaffer got his start as the leader of Saturday Night Live's band in the 1970s and was a feature player during the 1979-1980 season). And Zeus is RipTorn!
The best part? Come time for Recycled: The Series, Hades is still James Woods. And whenever Hades shows up in House of Mouse it's James Woods (well, except for "House of Villains", where he has all of two singing lines, so Rob Paulsen fills in). And in the Kingdom Hearts series it's James Woods again (well, except for Kingdom Hearts: Chain of Memories and Kingdom Hearts Coded, where his only lines are Boss Banter because of technical limitations, so archival clips of James Woods fill in). Woods loved doing the voice of Hades (partially because of his kids and partially because he loved the character) so much that he made a deal with Disney to do the voice of the character for whatever salary they ask for until his death.
Merv Griffin also plays a fictional "Merv Griffon" who interviews Herc as well in an episode.
Scott Weinger, Linda Larkin, Jonathan Freeman and Frank Welker reprise their "Aladdin" roles as Aladdin, Jasmine, Jafar and Abu for "Hercules and the Arabian Night," which was the Hercules-Aladdin crossover episode.
Keep Circulating the Tapes: One VHS tape, "Zero to Hero", was released. It is basically an expanded version of the episode "Hercules and the Yearbook", with roughly three full episodes to fill out the time. It served as a pilot for the series. The rest of the series has not been released on any home video format.
Missing Episode: At least four episodes were removed from rotation following 9/11, most notably Hercules and the Hostage Crisis which involved terrorists taking over Prometheus Academy, which was almost identical to the Columbine High School massacre.
Retroactive Recognition: Idina Menzel was already pretty well-known in the late 90s thanks to Rent, but her guest spot as Circe in the show is even funnier now, since she went on to appear in twolater Disney movies.
What Could Have Been: John Lithgow and Jack Nicholson were both offered the role of Hades, but turned it down.