Non-Fiction Books:
There are a lot of non-fiction books out there about fairies and many are best avoided, quite frankly. Some though are solid resources and worth reading.
A Dictionary of Fairies by Katherine Briggs - really anything by Katherine Briggs is good as she was an eminent folklorist of her time. This book is my choice to recommend because its one of my go-to's and is easy to use due its format.
The Good People: New Fairylore Essays edited by Peter Narvaez - a collection of more recent essays on the subject of fairylore from different Celtic countries, including a lot of anecdotal evidence. A modern version of 'The Fairy Faith in Celtic Countries'.
A Practical Guide to Irish Spirituality: Sli Aon Dhraoi by Lora O’Brien – a great overall introduction to modern Irish paganism that includes some good discussion on the Othercrowd. I’d also recommend the author’s older book, “Irish Witchcraft from an Irish Witch”
Fairy and Folktales of the Irish Peasantry by W. B. Yeats – a look at folklore and belief, especially fairylore.
The Gaelic Otherworld by John Campbell – an overview of Scottish folk beliefs and folk lore
The Fairy Faith in Celtic Countries by W. Y. Evans Wentz – the classic text on the Fairy Faith its a bit dated at this point having come out in 1911 but it includes fairy beliefs from a wide array of Celtic cultures.
Faeries by Brian Froud and Alan Lee – excellent artwork and some great tidbits of folklore sprinkled in
Elves, Wights and Trolls by Kveldulfr Gundarson – a look at Norse and German fairy beliefs and some comparison with the Celtic beliefs. Very useful for looking at how different closely related cultures viewed their fairies.
The Secret Commonwealth of Elves, Fauns and Fairies by reverend Robert Kirk – written in the 17th century its a short but fascinating look at traditional Scottish fairy beliefs
The Secret Commonwealth and the Fairy Belief Complex by Brian Walsh – a review and analysis of rev Kirk’s book but extremely insightful and should be read in addition to Kirk’s book for its commentary on beliefs about fairies
Meeting the Other Crowd by Eddie Lenihan and Carolyn Green – excellent book on Irish fairy lore
Fiction:
Most fiction that is based around fairies don't make a good resource here, for obvious reasons - its fiction. It was written by someone wanting to tell a good story not for the purpose of passing on actual belief or folklore. As much as we might like to think that fiction authors are actually inspired by real fairies or trying to tell a true story, much of the fairy fiction on the market is vastly at odds with traditional folklore. There are however some that are closer to traditional lore, and so I'm listing those here as resources.
The Faery Sworn Series by Ron Nieto - a trilogy about the granddaughter of a Fairy Doctor in Scotland who teams up with a kelpie to find her grandmother when she goes missing.
The Knowing by Kevin Manwaring - a story that builds off of the life and disappearance of rev. Robert Kirk.
Good Fairies of New York by Martin Miller - a bit whimsical but also gritty. Story about Celtic fairies coming to New York and those already there, how their lives collide with several humans.
Lords and Ladies by Terry Pratchett - part of Pratchett's Discworld series, and in fairness his other books are also good, but this one is my particular favorite for fairylore.
Youtube:
Ah Youtube. There's some really interesting stuff on there. Here's a couple videos I'd recommend
The Fairy Faith - a documentary that looks at fairy beliefs and anecdotes in America, Ireland, and the UK
Irish Fairylore: An Interview with Folklorist Dr. Jenny Butler - a great interview with someone who knows the subject well from an academic perspective
Folklore Collections by Michael Fortune - Michael Fortune is a treasure; he has spent time and effort recording interviews with people about their beliefs in different parts of Ireland.
Eddie Lenihan - there are a few videos of Eddie Lenihan on youtube and I highly recommend them. He is an amazing storyteller and very knowledgeable
Vimeo:
Not on youtube but really, really worth watching is the kin fables series on Vimeo.
Television and Movies:
Secret of Roan Inish - a movie about a family's multi-generational relationship with selkies, called rón in Irish.
The Spiderwick Chronicles - aimed at a very young audience, but seems to capture the idea of some traditional fairies
Pan's Labyrinth - fairly accurate, although very grim, depiction of fairies
Labyrinth - more lighthearted but truer to older folklore. A story of a girl trying to regain her baby brother from goblins; reminiscent of old changeling stories.