Significant Double Casting

Frequently in fiction, and especially in theatre, the same actor will play multiple roles. Sometimes this will just be for the sake of convenience, and not meaningful to the plot; after all, say it's the theatre -- if an actor is going to show up at the theatre every night to perform, you might as well take as much advantage of his or her skills as possible. However, sometimes there are reasons for the same actor playing two parts that are symbolic or have some subliminal impact in the story. Hence, Significant Double Casting.

The main distinction between this and the Acting for Two tropes is that almost all of the Acting for Two tropes operate on the assumption that the two (or more) characters look identical. Here, the point is merely that the two (or more) roles are intended to be played by the same person for some effect. So, in a way, this trope is a subtrope of Acting for Two, and a supertrope of some of the tropes listed on that page.

Anime

 * In Gaiking: Legend of Daiku-Maryu, Captain Garis and Daiya's father are both voiced by Tohru Ookawa, highlighting the captain's role as a father figure to Daiya.
 * The first Fullmetal Alchemist anime had both Trisha Elric and Sloth being voiced by the same actress; Sloth ends up being the Homunculus created when the brothers tried to transmute their mother.
 * In Slayers Evolution-R, the man who hires Lina to protect him from the assassin Zuuma has the same actor, hinting what his "long business trips" really are.
 * Ryoko shares the same seiyuu as in Senki Zesshou Symphogear.
 * Two cases of this in Fairy Tail, . When they revealed the cast for the first 12 episodes, Funimation didn't even bother hiding the first example. Admittedly, the second example is screwed up by mistake, but the revelation happened in the manga after recording for the first season of the dub had finished.
 * In Mobile Suit Gundam SEED, George Allster and Rau le Creuset are played by the same voice actor, which becomes significant when le Creuset encounters George's daughter Fllay and starts messing with her head.
 * In Mobile Suit Gundam SEED Destiny, Neo Roanoke is played by the voice actor who played Mu La Flaga in the previous series. Unsurprisingly, Neo turns out to be.

Film

 * Most of the named characters in The Wizard of Oz appear in Kansas at the beginning, and have similar roles in both worlds: the Wicked Witch/Mrs. Gulch as the antagonist, Professor Marvel/The Wizard as the charlatan who gets Dorothy into trouble, and three farmhands/traveling companions as moral support for Dorothy.
 * In Jumanji, Jonathan Hyde plays both Sam Parrish, Alan's father, and Van Pelt, the hunter. This highlights the fear Alan feels toward both characters.

Theatre

 * In the Alternate Show Interpretation of Assassins that was produced on Broadway, the Balladeer "becomes" Lee Harvey Oswald. Played by Neil Patrick Harris.
 * Peter Pan: Both Mr. Darling, the stern authority figure that tries to spoil the children's fun, and Captain Hook, the main antagonist also out to ruin the children's fun... by killing them, are usually played by the same person in productions and film adaptations
 * When Prior goes into Heaven at the end of Angels in America, each of the other seven actors in the show play a member of the Councilof Angels. When Prior wakes up afterwards in his hospital bed, he goes The Wizard of Oz on Belize, Emily, and Hannah ("And You Were There!").
 * Even in the HBO Miniseries--where some of the more outlandish uses of Significant Double Casting are ditched--Jeffrey Wright (Belize), Emma Thompson (Emily), Meryl Streep (Hannah), and Ben Shenkman (Louis) all still double as featured angels, and all four of them still appear in the scene after Prior wakes up.
 * Equus: The Young Horseman responsible for Alan's first riding experience also plays his favorite horse Nugget.
 * The Narrator in Blood Brothers plays several bit parts as well, all of which he plays for a reason. For example, he plays a bus attendant who breaks from reality briefly to impart ominous words to Mrs. Johnstone, before stepping back into character.
 * In Witness for The Prosecution, two roles are always double-cast for reasons which would be a huge spoiler.
 * In Into the Woods, the narrator is also another role, as part of breaking the fourth wall; also, the Big Bad Wolf is presented as um aroused, and his actor also plays one of the lecherous Charmings.
 * In Reefer Madness, one character who plays the Moral Guardian narrator also shows up in a number of other roles in the musical, including as Satan tempting the protagonists into using drugs. The implication confirmed at the end is basically that he is also an evil tempter in the Moral Guardian role.
 * In Speaking In Tongues, the nine characters (five male, four female) are played by four actors (two of each) across three acts.

Video Games

 * In Tales of the Abyss, a couple of the voice actors play more than one character for plot-important reasons - in each case, at least one of the characters they play . Therefore, in both the Japanese and English versions of the game, have the same voice actor, and  all share the same voice actress.
 * In Ever 17, Takeshi and the Kid have the same voice actor, though they are not voiced on their routes and can only be heard on the opposite route. Oddly enough,  To top it off,  is also voiced by the same actor in Drama CD.
 * In Persona 3, the protagonist, Ryoji,and Pharos all share the same voice actor in both the Japanese and English dubs. This is because
 * Subverted in Persona 4: only in the English version of the game do the protagonist and Adachi share a voice actor. This is likely because the directors wanted to give Johnny Yong Bosch more work to do.
 * In the Kingdom Hearts series, Sora is voiced Miyu Irino in the Japanese version and Haley Joel Osment in English, while his Nobody Roxas is voiced by Kouki Uchiyama/Jesse McCartney. When Birth By Sleep came out, new hero Ven looked like Roxas and shared his voice actor, while masked antagonist Vanitas had Sora's voice actor..

Western Animation

 * In Gargoyles, Kate Mulgrew played a bit role as Fox's mother. Then later she plays the voice of Titania, Queen of The Fair Folk. Coincidence? No. Turns out, they were the same person after all.
 * In Sym-Bionic Titan, the identity of the man behind G3 is all but explicitly stated--and one of the major giveaways is his voice actor.
 * In the Futurama movie Bender's Big Score, both Philip Fry and Lars Fillmore are voiced by Billy West. . However, Lars' voice is heavily distorted, and Billy West voices many other completely unrelated characters in the show, so even if the viewer does realize it's the same voice actor, many don't see the significance of it until The Reveal.