Changed your mind on West Side Story, did you? That’s still one I’d nominate. Aside from launching Sondheim’s career, it veered musical theater into a new, darker direction.

Obviously Oklahoma for being the first book musical.

Maybe Show Boat, not because of its attempt at being a book musical, but because it’s the first racially integrated broadway show.

Les Mis or something by Andrew Lloyd Webber — the shows that kicked off the megamusical trend. Maybe Jesus Christ Superstar would be considered the oldest of them, but Cats and Phantom had the staying power.

Rent, for incorporating pop rock into the score, creating the ticket lottery, and really establishing a musical fandom.

Honorable mentions: Hair, Cabaret, Fiddler on the Roof, A Chorus Line

I wouldn't want a list limited to five for the entire art form. But a few to consider: 

Cabaret, for the departure from the golden age, some confrontation of the audience if not fully immersive theatre, and Fosse.

Hair for rock music, youth culture, contemporary issues, and attracting poorer people to broadway.

The Last Five Years, idk if it's itself influential or just a really good study of what I see as 21st century Broadway. Small cast, fewer sets, small interpersonal conflicts, lyrics of... deliberate mundanity? Something. We wouldn't have Dear Evan Hansen, Come From Away, or Maybe Happy Ending without the Last Five Years I think.

The Producers reinvigorating comedies.

Mamma Mia and Jersey Boys' success ushering in one thousand jukebox musicals.

I think Company’s importance lies not only as a next step in concept musicals, but also in launching the golden age of Sondheim, particularly the Prince/Sondheim era that I think might be the most celebrated and influential partnership in the post golden age era.

Hamilton definitely belongs in the conversation, but I don’t know if I’d put it in top 5. We haven’t seen a whole lot of musical influence (no other major rap musicals) in the last 10 years, but I’d say we’ve definitely seen a huge shift in casting choices. Much more color-blind and color-conscious casting happening nowadays. This is significant.

I suppose how you define influence is the question here. Hamilton has had a very different influence than, say, Les Mis or West Side Story, and much less time to compare legacies.

Eh, I’ll give it to ya. That’s a valid one to put in one’s top 5 here. I don’t know what I’d omit from my own list to include it, but having it there is fair.

You've almost got one for each major decade here, which feels fitting. If you had a slot for the 90s Rent would definitely belong there (although I don't know what would represent the 2000s - Avenue Q?)

I think an argument could be made for Beauty and the Beast, as the first Disney stage musical.

There is a Romeo&Juliet musical, at least in German, I‘m unsure if there is an English version (there are versions in different languages, French for example but I‘m unsure if it’s the same musical as I haven’t seen/listened to either of them)

I don’t know of any other musical directly adapting a Shakespeare story

I think West Side Story is the next best thing as it’s inspired by Romeo & Juliet

The Lion King was inspired by Hamlet, if I remember correctly

Then there is &Juliet, that was inspired by Romeo&Juliet and uses some of its characters and also original characters plus Shakespeare and Anne Hathaway (his wife)

Something Rotten is not inspired by a Shakespeare story but is set in Shakespeare‘s time and features him as an important character

That’s all I can think of rn

Two Gentlemen of Verona won best musical

Something Rotten!

Kiss me kate

The Boys from Syracuse

Off the top of my head:

Man of La Mancha

Prettybelle

Dear World

The King and I

South Pacific

Flower Drum Song

Pipe Dream

Gigi

Camelot

Fiddler on the Roof

Kiss of the Spider Woman

Passion

By Jeeves

Cats

Natasha, Pierre, and the Great Comet of 1812

Breakfast at Tiffany’s

Edited to add the following, I just keep thinking of more and more:

Cabaret

Ragtime

Mary Poppins

Mame

Tuck Everlasting

Wicked

Once on This Island

Seussical

Matilda

James and the Giant Peach

Willy Wonka and the Chocolate Factory

The Great Gatsby

The Outsiders

Hamilton

Fun Home

Oliver!

The Color Purple

Gypsy

Carrie

The Lightning Thief

Anne of Green Gables

The Wizard of Oz AND The Wiz

Sweeney Todd, actually! It was adapted from The String of Pearls, one of the most well known penny dreadfuls!

Hamilton, based on the biography of the same name by Ron Chernow

Totally agree, but the musical is based on the book regardless. LOL

Wicked

Oh, and liberation that was good and relevant. And argue arguably John Proctor

Ragtime. The haves, the have nots. Injustice. Hoping for something better.

Parade - antisemitism, an unjust legal system weighted against minorities, racism

It was produced by several Chicago-area companies in the early 2020s after the pandemic restrictions were lifted. Facing a strange new fatal disease was not a difficult thing for young performers to relate to.

Urinetown. Basic life necessities are getting increasingly difficult for people to afford and the government disappears people.

Newsies…young people protesting an old rich dude, jessayin’.

A lot of musicals are still under copyright. Shakespeare is not.

New staging which is dramaticly different from the original isn't as common in musicals because audiences for musicals still enjoy the original. Most of the major operas have been performed so many times that audiences for operas want something new.

My personal opinion is a couple of reasons:

1. Copyright - anyone can stage a Shakespeare and Mozart and do what they want with it. They’ve been around so long that you need to reimagine them to attract interest, but you also get complete creative freedom. 
2. Demand - people in New York generally want to see the same show that people in London saw.

 

It does happen in musicals though. The Great Comet of 1812 looked vastly different in the US than the UK (with a bit of muttering). Meanwhile Phantom and Les Mis have both been restaged in the UK recently (though are still recognisably them).

Well Wicked is still in its original run, so the costumes and staging are the same. We’re still seeing the original director’s vision.

New Shakespeare productions, for example, have a new director each time that can direct the show within their vision.

Musicals that have the rights open to purchase will have a new director, costumes, sets, etc. Does that make sense?

Also, in regards to Wicked, the tours of it look exactly the same because those are tours of the Broadway production. They are not their own separate production. Usually, regional theatre companies are not able to license a show while it’s on Broadway, so they can’t do their own productions.

However, Wicked has allowed for a couple of international non-replica productions. If you do an image search for “Wicked Brazil” you can see the different set design.

If you really want to see how different productions of musicals can be, do an image search for “Sunset Boulevard 1993” and “Sunset Boulevard Jamie Lloyd” and see how different they look.

That is not a thing.

Edit after OP edit: What you are referring to is replica productions, which happen in all forms of theatre.

It depends entirely on the production. There can be majorly different interpretations of some musicals. Others are more regimented- Fiddler on the Roof comes to mind.

Secret Garden, Les Mis, Great Comet, Cabaret

Matilda was a book originally, I think there's also a musical based on James and the Giant Peach? Oh, and Oliver was originally a book if course. The Secret Garden too. Also The Time Traveller's Wife.

Is there a musical of The Book Thief too?

i can’t believe no one’s said wicked

I love posts like this - finding shows for a specific request! Hopefully this helps a little OP! 😄 If you’re looking anything else, just let me know! ✨

• Classics - Anne of Green Gables (multiple musicals), Lord of the Rings, Dracula, Frankenstein, Jekyll and Hyde, The Railway Children

• YA - Between the Lines (Jodi Picoult), Dusk: a bite-size love story (Twilight), Tyrell (GOT)

• Kids books - The Lightning Thief (Percy Jackson), The Creakers, Fancy Nancy, Freckleface Strawberry, Really Rosie, Diary of a Whimpy Kid, Dog Man, A Year with Frog and Toad

• History - Operation Mincemeat (The Man Who Never Was), Fantastically Great Women who Changed the World (kids book), Mrs Beeton Says (Mrs Beeton’s Book of Household Management)

Ragtime

West Side Story is one notable example.

the new Pirates of Penzance takes place in New Orleans

Sister Act. The movie was contemporary in 1992, they set the musical in the late 70s

Hadestown no longer ancient greece

The Comedy of Errors is set in Ancient Greece. Or, rather, both The Boys From Syracuse and The Comedy of Errors are set in the city of Ephesus at an unspecified time under either Greek or Roman rule. There are anachronisms and historical innacuracies in both, as is typical for Shakespeare, but the overarching setting of Ephesus constrains them as the city didn't last that long into the Common Era

Rent (based on La Boheme, set in Paris in the early/mid 1800s) 

Maybe Hamilton. A lot of social importance, the structure is unique and being hip-hop is innovating

Hamilton. But I can’t help but say “And although the news papers called it the Crime of the Century, Goldman knew it was only 1906… and there are 94 years to go! La la la”

hamilton.

• 11 tonys

•  a pulitzer prize

• a grammy

• an emmy

• a macarthur genius grant

• shoutout from the obamas, julie andrews, beyoncé and jay z, and PRINCE. THEE PRINCE. he liked it so much that he threw a party for the entire cast.

• praised by rap legends like nas, busta, black thought, andre 3000, jay z, and THE EMINEM. 

• studied in schools

• the only musical that has a crossover in pop culture (quoted in tons of shows, posters, etc.)

• the first musical recording from the 21st century to be inducted in the national recording registry

• increased the inclusion of poc, particularly black people on broadway

• the reason why the plan to replace alexander hamilton on the $10 bill got reversed (how many musicals have changed currency?) 

• a love letter to black artists & black art forms and eliza hamilton 

who knew a hip-hop musical about a forgotten founding father would be executed SO WELL. i’ve never seen a musical integrate r&b, jazz and hip-hop into one, like that is SO avant-garde for musical theatre. black-created genres sung by black artists and other artists of color in a white-dominated industry. isn’t that remarkable??

there will never be another musical like hamilton. it’s like “thriller” for musical theatre. nuff said.

Maybe Wicked since it did result in the IP for IPs sake for new musicals this century, not even then, Wicked was telling a story 99% of the audience wasn’t familiar, as opposed to just a straight remake of say, Beetlejuice,

Spring Awakening! Still set in the late 1800s, but now with rock music. 

West side story

I'm curious why you keep posting various different phrasings of this question here.

Honestly, I love how there's a bit of humor even in the actual historical Operation Mincemeat, just in how insane everything was and how big the personalities of all involved were (Charles Cholmondely actually studied bug mating habits for fun, and was genuinely described as "lolloping", for one, and that's not even getting started on Montagu). Not that it isn't a tone change, but still, the parts were kinda all there and semi-farcical to certain degrees already

Alice By Heart puts the characters in a ww2 bomb shelter

Natasha Pierre and The Great Comet of 1812 has some modern elements and references