I don't mind the idea of unnamed characters from the books being given names in adaptations per se, but I don't believe they need to do it, not everyone anyway. 

I think it made sense to give the White Witch's dwarf a name in the LWW movie because of how it reimagined her introductory scene. (Since the dwarf attacks Edmund and she calls him off, the dialogue flowed better with her being able to address him by name.) I also think it made a lot of sense to give Ramandu's daughter a name because...well, honestly, I never really understood why C. S. Lewis didn't give her a name. She marries one of the main characters and her death sets the plot of one book into motion. Seems like someone whose name you'd want to know.   

That being said, I'd really rather they didn't name the Lady of the Green Kirtle because she's supposed to be a mysterious character. Giving her a name would be more of a distracting flourish than anything IMO.

The hardest part of coming up with names for the characters would be inventing ones that meshed with the names C. S. Lewis created and sounded like they came from the same language. 

@col-klink  Most of the minor characters don't need names (entire crew of Dawn Treader, for instance!), but I agree with the ones you mentioned. 
@jasmine_tarkheena  Many of those names aren't necessary, sorry.  Emeth's unnamed older brothers just don't need names unless you write them as characters in the script. 
But you evidently had some fun inventing names, although I have to admit I winced at 'Mavis' for Jadis's sister.

Not sure if she needs one, but I must say I do like the name Esmeraldine for the Lady. It kind of suggests the word "Emerald." (I believe the blurb for the Silvet Chair on the back of the Collier versions even calls her the Emerald Witch, for some reason!) 

It would be helpful to have a name for Jadis' sister, but I'm afraid I must agree with Coracle's doubts about "Mavis"... it sounds a bit too real worldish. It might be helpful to reference some of the place names Jadis mentions in her list of conquests, like Sorloaz or Bramandin, llike calling her  Sorloa or Bramanda or Bramandina (or some variation on these with different consonants, e.g. Vorloa or Dramanda).

It is funny though that Lewis leaves out various major character names, yet feels compelled to tell us that Professor Kirke's non-appearing servants are named Ivy, Margaret and Betty!  

I'm not sure which ones that Cleander suggested for Jadis's sister- "Sorloa or Bramandina". But those are sure interesting ideas.

A movie or series could possibly give the White Witch's dwarf a name, like Walden did. I'm not sure if there's any that I could think of, since it probably won't be "Ginnabrik" again.

Walden named Mrs. Pevensie because that's the name of Georgie Henley's mother in real life. I picked either "Violet" or "Mary" for her.

"Apollo" sounds like a name for a noble stallion and Scarlet for a mare. Though Bree and Hwin's spouses would also probably need horse sounding names.

Douglas Gresham actually suggested the name "Liliandil" for Ramandu's daughter in the Walden adaptation. "Seren" is Welsh for "star", so I picked "Serena" for her.

On second thought about Emeth's six brothers, a movie or series still might do something with them, even a brief appearance. Emeth could probably be interacting with them in Aslan's country. They don't even have to be referred to by name.

I agree with names if it makes the dialogue flow better. Calling out "Hey you!" for each sailor, soldier, or servant would get tiring.

The Green Witch, I think it's better to leave nameless, because it does deepen the mystery of the character and makes her seem like she isn't human but a true force of evil.

@cobalt-jade 

Right. That is to say, not every sailor on the Dawn Treader has to be named.

I think back when The Silver Chair movie was in development, before Netflix took over, there was talk about that they were going to give the Green Lady a name. People were kind of divided on it. I picked "Esmeraldine", for "emerald", given that she's a green witch. But on second thought, it's possible to keep her nameless.

So some of the unnamed characters could be given names, but not all of them.

I think, as others have said, it depends on what role they play in the story and whether or not they need a name. Characters who only appear very briefly may not need a name at all. Characters who are only mentioned by another character and don't actually feature in person — like Jadis's sister or Emeth's brothers — almost certainly don't need a name, since they're not actually playing a role in the plot. (And the fact that Jadis never names her sister, while recounting their final battle, but just refers to her as "my sister", adds to our impression of how utterly cold-hearted she is — even though they're family, she won't dignify her rival for the throne by speaking her name. This is, after all, the woman who destroyed every living thing in their entire world rather than let her sister have the throne.)

It does make some sense to give the White Witch's dwarf a name, as he has a fair bit of screen time and it does sound better for the Witch to address him by name rather than "hey you!" The lack of a name for Ramandu's daughter in the books is surprising and sad, as it makes her more like a mere trope than a real character. But I hope any new production won't call her "Lilliandil". I cringe every time I read or hear that, sorry (and not just because I think the Walden films were a complete travesty). I'm sure Douglas Gresham meant well in coming up with it, but it's too transparently obviously a fairly old-fashioned name from our world — Lillian (which incidentally was my great-grandmother's name) — with a "dil" suffix that's apparently meant to make it sound exotic and fantastical, but to me it just comes across as a bad rip-off of Tolkien (too much like Eärendil).

I definitely agree the Green Witch doesn't need a name, and even if they give her one, it shouldn't be anything too much like a name from this world. As others have said, any new names invented for a new adaptation need to sound like ones that Lewis himself would have invented, and that's the difficult part. Not least because unlike Middle-earth, Narnia and its surrounding countries don't have any fully-worked-out invented languages that one can draw on to construct new names!! (And even that aspect of Tolkien's world seems to have escaped the writers of the recent Amazon spin-off. I haven't watched it, but I just about screamed when I heard they'd invented a female Elf called Bronwen, which is a perfectly ordinary Welsh name... )

I actually just recalled that in the Focus On The Family Radio Theatre adaptation of Prince Caspian, they combined Miss Prizzle and the other school mistress into one, and kept the name Miss Prizzle. I don’t know if a new adaptation will do that, though. If they're two different characters like they are in the book, I don't know if they're going to give the other school mistress a name.

It doesn’t really matter that much to me if they give names to characters without them such as Lilliandil in the Voyage of the Dawn Treader movie. I am really disappointed that they left Ramandu out. The movie would have been so much better if the scene with the retired star and birds was included as it was in the book.

@narnian78 

Right. I was actually kind of sad that Walden cut out Ramandu and his daughter didn't have enough screen time. As "Liliandil" sounds pretty, I don't see another adaptation using that name again.

For each of the children's parents, the only ones that are named in the books are Mabel (Digory's mother) and Harold and Alberta (Eustace's  father and mother). Digory mentions that his father is away in India, but is never referred to by name (I thought of "Albert", though on second thought, "Ebenezer".) The only time that Polly's parents are mentioned is that they sent her to bed without any dinner.  Jill's parents aren't mentioned at all.

(And even that aspect of Tolkien's world seems to have escaped the writers of the recent Amazon spin-off. I haven't watched it, but I just about screamed when I heard they'd invented a female Elf called Bronwen, which is a perfectly ordinary Welsh name... )

To be fair, all of Tolkien's high falutin' names were for royalty or characters good as royalty (the elves.) He didn't write about ordinary humans like peasants, blacksmiths, or farmwives. The hobbits, who can be considered his human peasant stand-ins, got ordinary names like Sam and Ned (even if they were shortened versions of more obscure names.)

Posted by: @cobalt-jade

To be fair, all of Tolkien's high falutin' names were for royalty or characters good as royalty (the elves.) He didn't write about ordinary humans like peasants, blacksmiths, or farmwives. The hobbits, who can be considered his human peasant stand-ins, got ordinary names like Sam and Ned (even if they were shortened versions of more obscure names.)

"Sam" was short for "Samwise" in The Lord of the Rings universe (I know that the word "universe" sounds a bit like a broad category, though). Not only that, but Sam marries a hobbit-girl named Rosie Cotton.

As for unnamed characters in Narnia, while some of them wouldn't be referred to by name, it does raise a lot of questions. It's never specified whether Mr. Pevensie and Alberta were brother and sister or if Harold and Mrs. Pevensies were brother and sister or if Alberta and Mrs. Pevensie were sisters.

While Jadis says that her sister was always a weakling, it raises the question was she really. Was she even as bad as Jadis was? I got the impression that Jadis was trying to find fault with her sister instead of taking responsibility for her own actions.

Digory mentions that his father is a way in India, though I have kind of wondered what kind of relationship he had with him. Perhaps writing letters about in regards to Mabel's health.

Aravis mentions in the backstory about how her mother died and how her father married another woman. She never mentions how her stepmother got into the picture. It raises the question whether it was arranged, like Aravis's was intended to be.

Posted by: @cobalt-jade

(And even that aspect of Tolkien's world seems to have escaped the writers of the recent Amazon spin-off. I haven't watched it, but I just about screamed when I heard they'd invented a female Elf called Bronwen, which is a perfectly ordinary Welsh name... )

To be fair, all of Tolkien's high falutin' names were for royalty or characters good as royalty (the elves.) He didn't write about ordinary humans like peasants, blacksmiths, or farmwives. The hobbits, who can be considered his human peasant stand-ins, got ordinary names like Sam and Ned (even if they were shortened versions of more obscure names.)

I was specifically referring to the fact that they'd chosen a human name from this world for an Elf. If the writers gave a name like Bronwen to a human character (of any social status), it wouldn't stand out as much. But the Elves have two well-developed Tolkien conlangs — Quenya and Sindarin — from which their names always come. There are enough Tolkien glossaries and name lists and fan sites run by enthusiasts of his languages that anyone could do a little research and construct a new Elvish name for a new character that would be consistent with the kinds of names Tolkien himself used. But no, they presumably just grabbed a slightly exotic-sounding "real-life" name that they must have figured looked Elvish enough. Well, Tolkien did base Sindarin quite heavily on Welsh, but they're still not the same language...  

But Bronwen wasn't an elf. She was a human woman in love with an elf.