I feel like all the Narnia books belong to basically the same genre (children's fantasy adventure), much as I'd prefer to say that they belong to different genres as it'd make for a more interesting discussion. But they are different kinds of stories. The best way to demonstrate this is by looking at them in terms of what the protagonists are trying to accomplish.

Both The Lion, the Witch and the Wardrobe and Prince Caspian are dramas about overthrowing tyrants and replacing them with good rulers. The Voyage of the Dawn Treader is quite different. It's a story about discovering new lands and strange creatures and phenomena. It's also sort of a quest story, but it's really more about the journey than the destination. In an upcoming interview on the Talking Beasts podcasts (which I've heard already because I'm a Patreon supporter; I don't mean that as a plug) the actors who played Caspian in the BBC miniseries and the Walden Media movie both described it as a story of self discovery, in which Caspian must find out who he's supposed to be, learning to reject greed and selfish ambition. I wouldn't go that far (Caspian's already portrayed as a good king at the beginning of the book), but I believe them to be on the right track.

The Silver Chair is a quest story, but one that's much more goal oriented with higher stakes. It has an overarching villain, but she's mostly in the background and while we can guess that she wants to use Rilian to conquer Narnia, we don't understand all the details until the book is almost over, making her different from Miraz or the White Witch. It's more like a mystery story in that way. The Horse and his Boy is a similar quest story with another background villain. But it has more chase scenes than The Silver Chair and is thus a bit more action oriented. The goal of the quest is also more personal than in the previous Narnia stories. The four main characters are all trying to find homes for themselves. 

The Magician's Nephew is...hard to define. Initially, the goal is for Digory to save Polly. But once in the Wood Between the Worlds, his goal becomes similar to Uncle Andrew's. Like with The Voyage of the Dawn Treader, it's a story about exploring new worlds, but here that turns out to be a bad thing. Halfway through, two goals emerge: stopping Jadis from doing harm and saving Digory's mother. In the climax, a choice has to be made between these two things.

I'm not saying this to criticize The Magician's Nephew at all. The constantly shifting goals mean the reader is never quite sure what's coming next, more so than in any other Narnia book.

The Last Battle has the most interesting structure. For the first two thirds, the goal is to save Narnia from bad guys, similar to the earliest books in the series. But it feels like this goal can never be accomplished. Every minor win for the heroes is followed by a major setback. It's really setup to be a tragedy.

Oh, that's a tough one.

The Lion, The Witch, and The Wardrobe- Bed-nobs and Broomsticks meets the Snow Queen

Prince Caspian- Hamlet, The Lion King

The Voyage of the Dawn Treader- The Odyssey

The Silver Chair- Similarities to the Hobbit

The Horse and His Boy- Arabian Nights

The Magician's Nephew- The Hobbit meets Science Fiction

The Last Battle- Arabian Nights meets the Apocalypse

Like Col Klink said, they're all in the fantasy genre. What's interesting is that more recently fantasy writers have leaned into the idea of borrowing from other genres to make their fantasy stories stand out in this wonderful but overpopulated genre... so you could maybe argue that Lewis was just 60 years ahead of the curve?!?!

As for each book, I'm not 100% sure, but here goes: 

LWW- Classic fairytale

PC- Revenge-plot Shakespearean drama

VDT- Epic adventure, akin to Odyssey (just had to steal from you, @rose)

SC- while it is Arthurian in plot (heroic quest), some elements, like a half-serpent monster who breathes falsehoods and a mind-bending ruler of an underground kingdom, are borrowed from the Edmund Spenser's The Faerie Queene and the allegorical folktale of The Mountain-King. So... maybe medieval/Renaissance allegory?

HHB- Arabian nights, coming of age story.

MN- I'm not sure if I consider this science fiction. It's more like magic fiction, not unlike Harry Potter, but magic is less whimsical and much more of a forbidden, dangerous art.

LB- Tragedy... with a happy twist? And also yes, apocalyptic. 

Posted by: @the-mad-poet

PC- Revenge-plot

That's interesting. I wouldn't really think of it that way since Caspian, the one who says he wants to avenge someone, doesn't end up killing Miraz. I guess you could say that Narnia, in general, is getting revenge on the Telmarines.

I should clarify, I definitely think that all of The Chronicles of Narnia books are in the children's fantasy genre. I meant what other genre(s) each book is most like. I have updated the title of the thread for hopefully a bit more clarity!

Posted by: @col-klink

In an upcoming interview on the Talking Beasts podcasts (which I've heard already because I'm a Patreon supporter; I don't mean that as a plug)

By all means plug the Patreon and the podcast.

Posted by: @jasminetarkheena

The Silver Chair- Similarities to the Hobbit

That's interesting; I've never thought of SC as being similar to The Hobbit! Good thoughts about Hamlet for Prince Caspian, too. That jives with @the-mad-poet's thought on PC being like a Shakespearean drama.

Posted by: @the-mad-poet

What's interesting is that more recently fantasy writers have leaned into the idea of borrowing from other genres to make their fantasy stories stand out in this wonderful but overpopulated genre... so you could maybe argue that Lewis was just 60 years ahead of the curve?!?!

In my opinion, he usually was.

Posted by: @the-mad-poet

SC- while it is Arthurian in plot (heroic quest), some elements, like a half-serpent monster who breathes falsehoods and a mind-bending ruler of an underground kingdom, are borrowed from the Edmund Spenser's The Faerie Queene and the allegorical folktale of The Mountain-King. So... maybe medieval/Renaissance allegory?

I think that broader definition definitely applies; Arthurian romance is perhaps a bit too specific.

Posted by: @the-mad-poet

MN- I'm not sure if I consider this science fiction. It's more like magic fiction, not unlike Harry Potter, but magic is less whimsical and much more of a forbidden, dangerous art.

True, I don't think MN calls to mind most people's idea of science fiction, but the whole concept of the rings, the way they were used, Uncle Andrew's experiments, the death of a universe and the birth of another — it makes me think of very early science fiction. A genre of which I am not an expert in the slightest. I think A Connecticut Yankee in King Arthur's Court is considered science fiction, yes? I don't think I ever finished that...

@rose

"That's interesting; I've never thought of SC as being similar to The Hobbit!"

It's similar to The Hobbit because in both stories, the characters journey North, and they encounter rock-throwing giants. Both stories have giants that throw rocks as part of a game.

 

Posted by: @jasminetarkheena

It's similar to The Hobbit because in both stories, the characters journey North, and they encounter rock-throwing giants. Both stories have giants that throw rocks as part of a game.

Well, "stories about giants who hurl rocks" doesn't really count as a genre but we are defining "genre" rather loosely for the purposes of this thread, so I guess you could say that.

I admit that, while I definitely believe that the individual Narnia books are unique, I don't see them as surprisingly different as people like Michael Ward do. I think they are as different and similar as you'd expect seven books in one series by an author, who had a specific style and themes but wasn't going to just repeat himself in every entry, to be. 

@col-klink Good point!

@col-klink ,

I think the similarities to Hamlet were what influenced me to dub Prince Caspian as a revenge plot (which i in hindsight realize is more a plot style than genre, but I digress 😀)

 But that said, I think your idea of Narnia in general getting revenge on the Telmarines could still justify the revenge-plot label quite nicely!