A comprehensive list of official ‘Twilight’ social networking sites

Anna Kendrick's Twitter photo

While a list of official Twilight Twitter pages has already been made here, it needs a bit of updating, and rather than solely modifying the original list from last summer, I thought that it might be helpful to expand the coverage of the material and include as much access information about the writers, cast, filmmakers, and musicians associated with Twilight, The Twilight Saga: New Moon, and The Twilight Saga: Eclipse as could be found to be official.   
That said, I've put together a comprehensive list of all of the known official websites as well as Twitter, MySpace, YouTube, and Facebook pages associated with each person or group.
The hope is that this will aid you all in avoiding imposter accounts and websites as well as help you connect with your favorite Twilight personalities!
As of the writing of this article, these are the only official webpages for the persons listed, but if new information about official accounts becomes available, I will be glad to update this post.
Please do note in advance that Robert Pattinson (“Edward Cullen”), Kristen Stewart (“Bella Swan”), and Taylor Lautner (“Jacob Black”) are absent from the list as they do not have official websites, Twitter accounts, Facebook pages, MySpace pages, YouTube sites, or the like. Any such site claiming to be one or more of these three persons is fictitious. Others also absent (Dakota Fanning (“Jane”), for example) should be presumed not to have official pages for the same reasons.
Hope you enjoy!

Books

Stephenie Meyer (Author, Twilight series books and The Host)

Official website - StephenieMeyer.com

Little, Brown and Company (Publishing group, Twilight series and The Host)

Official website - HatchetteBookGroup.com
The Twilight Saga - TheTwilightSaga.com

Filmmakers

Summit Entertainment (Film studio, Twilight series films)

Official websites - NewMoonTheMovie.com, EclipseTheMovie.com, Summit-Ent.com
Official Facebook Fan Page – Facebook.com/Twilight
Official MySpace page – Myspace.com/Twilight
Official Twitter page – @Twilight
Official YouTube page – Youtube.com/OfficialTwilightFilm

Melissa Rosenberg (Screenwriter, Twilight series films)

Official Facebook page - Facebook.com/Melissa.Rosenberg

David Slade (Director, The Twilight Saga: Eclipse)

Official Twitter page – @David_A_Slade

Cast

(in alphabetical order by last name)
 

Charlie Bewley ("Demetri")

Official website - CharlieBewley.com
Official Twitter page - @Alchemission

Gil Birmingham ("Billy Black")

Official website - GilBirmingham.com
Official Facebook page - Facebook.com
Official MySpace page - MySpace.com/GilBirmingham
Official Twitter page - @GilBirmingham

Jamie Campbell Bower ("Caius")

Official Twitter page - @JamieBower

Cameron Bright ("Alec")

Official Twitter page - @CameronBright

Billy Burke ("Chief Charlie Swan")

Official Twitter page - @Billy_Burke

Justin Chon ("Eric Yorkie")

Official Twitter page - @JustinChon
Official YouTube page - YouTube.com/JustinChon

Daniel Cudmore ("Felix")

Official Facebook page - Facebook.com
Official Twitter page - @DanielCudmore

Peter Facinelli ("Dr. Carlisle Cullen")

Official website - Peter-Facinelli.com
Official Facebook page - Facebook.com
Official MySpace page - MySpace.com/PeterFacinelli
Official Twitter page - @PeterFacinelli

Jodelle Ferland ("Bree Tanner")

Official Twitter page - @JodelleMicah

Edi Gathegi ("Laurent")

Official MySpace page - MySpace.com/FrameWorkEdi
Official Twitter page - @IamEdiGathegi

Kiowa Gordon ("Embry Call")

Official MySpace page - MySpace.com/KiGordon
Official Twitter page - @CircaKiGordon

Ashley Greene ("Alice Cullen")

Official Twitter page - @AshleyMGreene

Anna Kendrick ("Jessica Stanley")

Official Twitter page - @AnnaKendrick47

Tinsel Korey ("Emily Young")

Official Website - TinselKorey.com
Official charity page - 4real.com/TinselKorey
Official MySpace page - MySpace.com/TinselKorey
Official YouTube Page - @TinselKorey

Rachelle Lefevre ("Victoria" in Twilight and The Twilight Saga: New Moon)

Official charity page - Susan G. Komen
Official Twitter page - @RachelleLefevre

Alex Meraz ("Paul")

Official MySpace page - MySpace.com/NomaK1000
Official Twitter page - @TheAlexMeraz

Christian Serratos ("Angela Weber")

Official MySpace page - MySpace.com/ChristianSerratosMusic
Official Twitter page - @CSerratos

Michael Sheen ("Aro")

Official Twitter page - @MichaelSheen

Chaske Spencer ("Sam Uley")

Official website - ChaskeSpencer.com
Official Facebook page - Facebook.com
Official MySpace page - MySpace.com
Official Twitter page - @TheRealChaske

Boo Boo Stewart ("Seth Clearwater")

Official MySpace page - MySpace.com/ActionBooBoo
Official Twitter page - @Mammarazzi1 (shared with sister and mother)

Solomon Trimble ("Sam" in Twilight)

Official MySpace page - MySpace.com/SolomonTrimble

Michael Welch ("Mike Newton")

Official website - MichaelWelchOnline.com
Official Facebook page - Facebook.com
Official MySpace page - MySpace.com/OfficialMichaelWelch

 

Score Composers

Carter Burwell (composer, Twilight)

Official website - CarterBurwell.com

Alexandre Desplat (composer, New Moon)

Official website - AlexandreDesplat.net

Howard Shore (composer, Eclipse)

Official website - HowardShore.com

Soundtrack Musicians

(in alphabetical order)
 

Anya Marina ("Satellite Heart," New Moon)

Official website - AnyaMarina.com
Official Facebook page - Facebook.com/AnyaMarinaMusic
Official MySpace page - MySpace.com/AnyaMarina
Official Twitter page - @AnyaMarina
Official YouTube page - YouTube.com/AnyaMarinaMusic

Band of Skulls ("Friends," New Moon)

Official website - BandofSkulls.com
Official MySpace page - MySpace.com/BandofSkulls
Official Twitter page - @BandofSkulls
Official YouTube page - YouTube.com/BandofSkulls

Bobby Long (co-writer, "Let Me Sign," Twilight)

Official website - MusicBobbyLong.com
Official Facebook page - Facebook.com
Official MySpace page - MySpace.com/MusicBobbyLong
Official Twitter page - @BobbyLongNews
Official YouTube page - YouTube.com/MusicBobbyLong

Black Rebel Motorcycle Club ("Done All Wrong," New Moon)

Official website - BlackRebelMotorcycleClub.com
Official Facebook page - Facebook.com
Official MySpace page - MySpace.com/BlackRebelMotorcycleClub
Official Twitter page - @BRMCOfficial
Official YouTube page - YouTube.com

Blue Foundation ("Eyes on Fire," Twilight)

Official website - DPC-rec.dk
Official MySpace page - MySpace.com/BlueFoundationDenmark
Official Twitter page - @BFHome

Bon Iver (co-performer, "Roslyn," New Moon)

Official website - BonIver.org
Official MySpace page - MySpace.com/BonIver

Collective Soul ("Tremble for my Beloved," Twilight)

Official website - CollectiveSoul.com
Official Facebook page - Facebook.com/CollectiveSoul
Official MySpace page - MySpace.com/CollectiveSoul
Official Twitter page - @Collective_Soul
Official YouTube page - YouTube.com/CollectiveSoulTV

Death Cab for Cutie ("Meet Me on the Equinox," New Moon)

Official website - DeathCabforCutie.com
Official Facebook page - Facebook.com/DeathCabforCutie
Official MySpace page - MySpace.com/DeathCabforCutie
Official Twitter page - @DCFCTours
Official YouTube page - YouTube.com/DCFCTV

Editors ("No Sound but the Wind," New Moon)

Official website - EditorsOfficial.com
Official Facebook page - Facebook.com/EditorsMusic
Official MySpace page - MySpace.com/EditorsMusic
Official YouTube page - YouTube.com/EditorsOfficial

Grizzly Bear ("Slow Life, New Moon)

Official website - Grizzly-Bear.net
Official MySpace page - MySpace.com/GrizzlyBear

Hurricane Bells ("Monsters," New Moon)

Official Facebook page - Facebook.com/HurricaneBells
Official MySpace page - MySpace.com/HurricaneBells
Official Twitter page - @HurricaneBells

Iron & Wine ("Flightless Bird," Twilight)

Official website - IronAndWine.com
Official Facebook page - Facebook.com
Official MySpace page - MySpace.com/IronAndWine

Linkin Park ("Leave Out All the Rest," Twilight)

Official website - LinkinPark.com
Official Facebook page - Facebook.com/LinkinPark
Official MySpace page - MySpace.com/LinkinPark
Official Twitter page - @LPUnderground
Official YouTube page - YouTube.com/LinkinParkTV

Lykke Li ("Possibility," New Moon)

Official website - LykkeLi.com
Official Facebook page - Facebook.com/LykkeLiOfficial
Official MySpace page - MySpace.com/LykkeLi
Official Twitter page - @Lykke_Li
Official YouTube page - YouTube.com/LykkeLiVideos

Marcus Foster (co-writer, "Let Me Sign," Twilight)

Official MySpace page - MySpace.com/MarcusFoster
Official Twitter page - @MarcusFoster1

Muse ("Supermassive Black Hole," Twilight; "I Belong to You," New Moon)

Official website - Muse.mu
Official Facebook page - Facebook.com/Muse
Official MySpace page - MySpace.com/Muse
Official Twitter page - @Muse
Official YouTube page - YouTube.com/Muse

MUTEMATH ("Spotlight," Twilight)

Official website - MUTEMATH.com
Official Facebook page - Facebook.com/MUTEMATH
Official MySpace page - MySpace.com/MUTEMATH
Official Twitter page - @MUTEMATH
Official YouTube page - YouTube.com/MUTEMATH

OK Go ("Shooting the Moon," New Moon)

Official website - OKGo.net
Official Facebook page - Facebook.com/OKGo
Official MySpace page - MySpace.com/OKGo
Official Twitter page - @OKGo
Official YouTube page - YouTube.com/OKGo

Paramore ("I Caught Myself" and "Decode," Twilight)

Official website - Paramore.net
Official Facebook page - Facebook.com/Paramore
Official MySpace page - MySpace.com/Paramore
Official Twitter pages - Source
Official YouTube page - YouTube.com/Paramore

Perry Farrell ("Go All the Way (Into the Twilight)," Twilight)

Official website - PerryFarrell.com
Official Facebook page - Facebook.com
Official MySpace page - MySpace.com/PerryFarrell
Official Twitter page - @PerryFarrell

Sam Bradley (co-writer, "Never Think (Too Far Gone)," Twilight)

Official website - SamBradley.com
Official MySpace page - MySpace.com/SamBradley
Official Twitter page - @SamuelTwitt1

Sea Wolf ("The Violet Hour," New Moon)

Official website - SeaWolfMusic.com
Official Facebook page - Facebook.com
Official MySpace page - MySpace.com/SeaWolf
Official Twitter page - @SeaWolfMusic

St. Vincent (co-performer, "Roslyn," New Moon)

Official Twitter page - @St_Vincent

The Black Ghosts ("Full Moon," Twilight)

Official MySpace page - MySpace.com/BlackGhosts

The Killers ("A White Demon Love Song," New Moon)

Official website - TheKillersMusic.com
Official MySpace page - MySpace.com/TheKillers
Official Twitter page - @TheKillers

Thom Yorke ("Hearing Damage," New Moon) 

Official MySpace page - MySpace.com/ThomYorkeMusic