I picture Jill with chin-length, wavy hair that is either dirty blond or light brown.

I think it would be best to get an actress who is short and small-framed. And most importantly, she must be someone who can portray a feisty spirit that more than makes up for that smallness.

~Riella

Jill Pole:

Appearance & Personality: between 5'1 and 5'4 depending on the age the cast her at. Shoulder length brown hair. She doesn't strike me as one who cares much about a particular style, so something simple and non fussy for a hairstyle. Green or hazel eyes. Capable of smirking without actually showing it and capable of showing a snarky side, a gentle side, and a determined side.

I've always pictured Jill as someone who starts out almost as a drab blend into the background type that grows and matures through her time in Narnia into a true lady of Narnia. Not the wilting flower genteel type, but someone similar to Lucy, but a little more feminine. We know she has the potential for a sneaky streak based on the LB, so that's why I always pictured her with a bit of snark and a lot of determination.

I'd imagine Jill as someone rather short for her age, and maybe a bit behind in her schoolwork, due to forgetting what it was she was supposed to do and also being bullied. Maybe that is enough in itself for fellow students to think they could get away with bullying her, especially if her surname is a contrast to her appearance. I'd also see her as having hidden strengths that she, herself, has yet to discover, such as her acting ability at Harfang.

I'd think of Jill Pole as a bit grotty and untidy because she forgets where she puts things sometimes, but mainly because that is the way she would be force to be on the long journey to Harfang and elsewhere. Little or no time for a wash, you see. But that doesn't mean she can't appreciate nice clothes and people being nice to her. In Narnia, it is Jill who first suspects that the woman who enticed Rilian was probably the snake as well. It is hard to pick Jill's character as it grows whilst she learns that everyone who seems nice is not necessarily well-intentioned, and that even nasty people like her nasty schoolmates are not always what they seem.

I'd expect a competent actress to bring out these points, but I am at a loss about how she would look. Probably nothing special, such as having brown hair and hazel eyes, the lot of many. At least brown hair and hazel eyes are better to have than dismally grey hair and eyes that need medical attention, as Jill would agree in LB.

Yes, I believe it was mentioned somewhere in one of the books, (I think The Last Battle) that Jill is short, or at least shorter than Eustace if I remember correctly.

I think the BBC adaptation caught Jill's appearance perfectly. She had blue eyes, light brown hair with some waves in it, etc. As long as they cast somebody of English ancestry, I'll feel fine with however Jill may look.

I always imagined her with dark hair, not black, but dark brown with green eyes, I always imagined with straight hair up to her shoulders. Although I really liked The Lady Arwen Undómiel's pictures. I really like the way she looks.
I also remember reading something about her being a bit short. I always did imagine her as kind of a small fighting-spirited sort of girl. And it does say in the LB that she did archery, no? Or am I mixing something?
I agree with Louloudi the Centaur that for me is not her looks but her character. She has a very interesting character I think, and it might be a bit difficult to portray her in film, so she won't come out looking stuck up.