NOTE: An actor "playing the same character over and over" is often a comedian playing themselves, or simply someone with a lack of range. Either way, think long and hard about whether they truly qualify for this trope before adding them.
In a strange and rare example of the Expy not originally being an expy and then being one and being played by the person the character is an expy off, the live action Scooby-Doo movie has Daphne go though off screen character development that includes a shitton of levels in badass that makes her basically a bit more girly girl, non-superpowered version of Sarah Michelle Gellar's (who plays her) most famous character.
The character of Han, played by Sung Kang, in the Fast and Furious films is the same Han (also played by Kang) in the indie film Better Luck Tomorrow.
Norman Bates of Psycho and David Callaway in Hide and Seek have similar characteristics. They are protagonists of their films, they fight antagonists not shown to us, they found out that they themselves are the antagonists, and they have a Split Personality Takeover afterwards.
Despite the use of many other characters from the comics, the Batman movies also have Expys for some characters. For instance, since, for some reason, Tim Burton didn't want to use Harvey Bullock (possibly because Bullock's character wasn't truly corrupt) in the 1989 Batman movie, he created the overweight, gruff, corrupt Lt. Eckhardt in the Batman movie. In the Dark Knight Trilogy, you have Officers Stevens and Ramirez, who are essentially Expys for Harvey Bullock and Renee Montoya, with the exception of, again, being that Ramirez is corrupt. Stevens on the other hand is Bullock right down to the toothpick chewing but his name was probably changed so the film wouldn't have two characters named Harvey.
Another corrupt detective in the Dark Knight Trilogy, Flass in Batman Begins, is also somewhat Bullock-like. This is particularly interesting since he's named for a character in Batman: Year One who was a Corrupt Cop, but wasn't in any way a Fat Slob.
John Cusack's Hitman with a Heart in War Inc. is an expy of his character in the earlier film Grosse Pointe Blank, and almost every other character in the new film has an equivalent in the previous one.
Alex from Home Alone 3 is the expy of Kevin from the previous two movies.
Daniel Jackson (Stargate) vs. Milo Thatch (AtlantisTheLostEmpire). An awkward, orphaned, linguist who becomes a laughing stock among his peers. Using his skills with language, he translates something that allows him to actually go to the place that proves his theories were correct. The team of people with him dislike him, but he slowly gains their respect. In the end, he decides to stay with the hot chick he met in Atlantis/Abydos.
Star Wars, a lot of the characters from the Prequel Trilogy are Expies of characters from the Original Trilogy (Even if both characters are actually in the original trilogy)
Anakin Skywalker in episodes II and III is basically an Expy of his own son, even though he was also The Dragon in episodes IV, V, VI and even the end of III.
Qui-Gon Jin is The Obiwan TO Obi-Wan Kenobi, and is an expy of his own apprentice basically.
Darth Maul is obviously an Expy of Darth Vader in a The Dragon sort of way. Count Dooku is also an Expy of Darth Vader, but he's actually got more in common with The Emperor, and is more of a TheStarscream than a TheDragon. General Greivous is a bit closer to Vader; Darth Vader has trouble breathing, Grevious has a cough, and they're both cyborgs.
Word Of God says the three were used in foreshadowing, each one being an element of Vader. Maul as The Dragon who enforces the emperor's will, Dooku as a fallen Jedi, and Grievous as a cyborg with breathing problems (though he only got them after Mace Windu used the Force to crush his chest).
This sort of thing is so common in the Star Wars Expanded Universe that you may well assume the Star Wars galaxy is heavily based on reincarnation, maybe through the Force. Just look at Han Solo via Atton Rand, Carth Onasi, Kyle Katarn (before the lightsaber), Corran Horn...
Don't forget Darth Malak, possibly the most obvious Darth Vader expy, and Cad Bane, an (unfortunately much more talkative) expy of Boba Fett.
In Gremlins 2: The New Batch, one Mogwai looks and acts very similarly to Stripe from Gremlins. The music sting, the way the camera zooms in and Gizmo's reaction all make it abuldantly clear to everyone including Gizmo that, for all intents and purposes, Stripe has been reborn. (Technically, both characters are brothers, as they both popped out of Gizmo's back after he got wet, and the New Stripe has black and white fur rather than blue and white, and after he becomes a gremlin, he has a reptilian frill rather than a Mohawk. But still undeniably an expy of Stripe.)
Terminator Salvation Marcus, in several ways, is an Expy of Arnold/the T-800, especialy in Terminator 2, and to a lesser extent, Kyle Reese in the first Terminator movie. Marcus is basically a Prototype for the T-800, as he actually has a metal endo skelton and his outsides are living tissue. Unlike the T-800, however, he still has a human brain and thinks he's human. There's numerous little bits of action that remind you of Arnold, he kind of looks like a younger, skinnier Arnold, at his execution you actually EXPECT him to say "I'll Be Back" as his last words because they were just talking about bring him back to life the the VERY PREVIOUS SCENE (Instead, he just shrugs when asked for any last words) and, amusingly, when the humans chain him up after discovering his metal skeleton, his wrists are chained to a barbell. But even WITHOUT Marcus, the movie has numerous little homages to the previous movies.
The villains in each of the direct sequels to Highlander — Katana in Highlander II, and Kane in Highlander III — were pale imitations of the Kurgan, the awesomely memorable villain from the original. Kane even had the same deep, rough Dr. Claw voice as the Kurgan.
Likewise, the villain from the TV series' pilot "The Gathering", Slan Quince, was also a Kurgan expy.
And the Guardian from Highlander: The Source, particularly in his habit of incessantly cracking jokes. And even Jacob Kell from Endgame has shades of Kurgan-expy-ness.
That was one of the attractions of the series - villains who actually weren't copies of the Kurgan.
The Strangers with Candy film introduced Megawatti as an obvious expy for Orlando from the series because the actor who played him was too old to reprise the role.
In the Marx Brothers film each brother plays a character with a different name but the same personality as the character he played in the other films.
As do some of the recurring supporting actors, most notably Margaret Dumont.
Transformers II Revenge of the Fallen; In Transformers 1, of course, they couldn't have a giant robot turn into outdated '80s technology so they had an expy of Soundwave by taking one of Soundwave's tapes (Frenzy) and turning him into a CD player. In Revenge of the Fallen, they turn Soundwave himself into a satellite, and he sends another one of his tapes, Ravage, to Earth to spy on the humans. The whole Expy thing becomes a bit Meta, because Ravage spews a bunch of little metal balls which come together and form another character who is an expy of Movie 1's Frenzy!
Ravage also has a compartment in his chest open to release The Doctor, just as the old Soundwave used to release cassette-Ravage.
Not to mention the fact that Blackout in the first movie was an Expy of Soundwave. His role was originally meant to be filled by Soundwave, down to the symbiotic animal partner.
There's also Wheelie. He has some similarities to both Frenzy and Rattrap from Beast Wars.
Jetfire, bit of an Expy of Kup.
Both Coraline and MirrorMask are about a dark haired, odd, creative girl, who discover a strange fantasy world that is ruled by an Evil Counterpart of the girl's mother who wants to take over the girl's mind in a manner that turns her eyes black. Although MirrorMask is a bit more complicated. There are a total of THREE versions of Helena's mother, TWO of them are in a coma, while in Coraline, the Antagonist is the Other Mother, the Dark Queen in MirrorMask is really just worried about where her daughter is. The REAL antagonist is the Evil Counterpart of Helena, and the two are never even in the same universe at the same time!
Léon is Victor from Nikita. Same actor, and they even share an euphemism for their job, "cleaner".
Luc Besson has said that they're basically cousins.
Winston Wolf, "the cleaner" from Pulp Fiction, is an Expy of the character played by Harvey Keitel in The Point of No Return — which was itself a remake of Nikita, thus tying all of these fellas together.
Al from Toy Story 2 and Dennis Nedry from Jurassic Park are played by Wayne Knight, and they have similar personalities. They are both fat, disgusting, immoral (Al stole a child's beloved toy, for God's sake!), nerdy slobs. Karma bites both of them in the ass eventually.
Both are of course an Expy from the original evil himself, Newman!
Victor◊ from Corpse Bride looks too much like grown-up Vincent◊, what was one of Tim Burton's first projects. The resemblance is even lampshated in the film when Mr Everglot acidentally calls him Vincent.
Victor also looks like what Jack Skellington would look like if the latter was alive, albeit with a tear-drop-shaped head rather than a round skull.
The Filipino superhero Captain Barbell is quite similar to Captain Marvel, except that he has no lightning power and that his wimpy alter ego has to lift a barbell over his head to transform.
Sort of a type-casting example with Paul Bettany. He recently was in a biopic on Charles Darwin, and some reviews noted his previous role as Stephen Maturin in film Master and Commander who comes across as somewhat similar to Darwin in his time on the Beagle (intellectual naturalist on a ship, interacts with giant tortoises at one point).
Not any giant tortoises. The giant tortoises of the Galpagos Islands, just like Darwin!
Rudolph the Red-Nosed Reindeer: The Movie, a mild Cult Classic movie version of the classic song, has a few of these. Clarice is replaced with Zoey, who was supposed to be named "Clarice" but they couldn't get the copyrights. Rudolph's rival Arrow looks very much like Fireball.
Ditto for Jesse Eisenberg, whose appearance has been compared to Cera by some. His character in Adventureland is basically like the guy from The Squid And The Whale growing up and graduating college. Zombieland is what'd happen if either one was stuck in a Zombie Apocalypse.
Subverted with Eisenberg's role in The Social Network, although he's still playing a college kid.
Ditto for Seth Rogen, who plays a fat clumsy pothead in pretty much all of his movies, and Jonah Hill, who plays mini-Seth Rogen in pretty much all of his movies.
Subverted, hard, by Seth Rogen in Observe and Report, so much so that many saw his character as a Complete Monster. However, this also demonstrated considerable range, as his character was so completely different from any of the other characters he played.
In 2012, the main characters as well as plot elements are very similar to Steven Spielberg's The War of the Worlds. For example, the father, played by Tom Cruise/John Cusack, sucks as his job. His ex-wife, played by Miranda Otto/Amanda Peet has encountered someone else, and their two kids played by Justin Chatwin/Liam James and Dakota Fanning/Morgan Lily don't like Tommy/Johnny as much as their new stepfather. And then disaster strikes.
The scene with the arks may also resemble the ferrys.
George Sanders' The Falcon was a expy of George Sanders' The Saint. The Saint's author even brought suit against RKO over the issue.
The main characters in Buckaroo Banzai are all Expies of Doc Savage and his boys. Likewise, Buckaroo's unseen nemesis, Hanoi Xan, is an Expy of another pulp literary character, Fu Manchu.
In Dagon Paul Marsh seems to be a deliberate homage to Jeffrey Combs.
William Gibson's recurring character Molly Millions was present in the book of Johnny Mnemonic, but was missing from the filmed version (also absent were quality writing, believable acting, and entertainment value). She was replaced with a near-identical character named Jane. The rumour is that this change was made because of some arguments about the film rights for Gibon's novel Neuromancer, in which Molly also appears.
In Return to Oz, Dorothy's new companions are not quite so different from her first companions from her first visit in Oz. Billina = Toto, Tik-Tok = the Tin Man, Jack = the Scarecrow, and the Gump = the Cowardly Lion.
David Lynch wrote Mulholland Drive as a television pilot, and some believe a potential sequel to Twin Peaks. Lynch enthusiasts argue that the character of Betty/Diane in Mulholland Drive is an Expy of Audrey Horne on Twin Peaks.
