I know some of these aren't really the most suited towards Rock Band, but I want to make it happen anyway. Expect many additions over time.

30 Seconds to Mars
A Perfect Circle
A Tribe Called Quest
Agalloch
Air
Alice in Chains
The Allman Brothers Band
Altar of Plagues
American Football
Andy Stott
Animal Collective
Animals as Leaders
Aphex Twin
Arctic Monkeys
Arcturus
Ariel Pink
Ash
Asobi Seksu
Atheist
Autechre
The Avalanches
Ayreon
Baroness
The Beach Boys
Beastie Boys
Beck
Belle and Sebastian
Between the Buried and Me
Big Black
Biosphere
Bjork
The Black Keys
Black Sabbath
Bloc Party
Blue Oyster Cult
Boards of Canada
Bob Dylan
Boredoms
Boris
Brand New
Brave Little Abacus
Brian Eno
Burial
Can
Candy Claws
Cap'n Jazz
Car Seat Headrest
Caravan
Carly Rae Jepsen
Casualties of Cool
The Chameleons
Charles Mingus
CHVRCHES
Circa Survive
Circus Maximus
cLOUDDEAD
Cocteau Twins
Coheed and Cambria
Converge
Cornelius
Cream
The Cure
Cynic
Daft Punk
Dalek
Danny Brown
David Bowie
Deafheaven
The Dear Hunter
Death
Death Grips
Deathspell Omega
Deep Purple
Deftones
Deltron 3030
Depeche Mode
Devin Townsend
Digable Planets
Dinosaur Jr.
DJ Shadow
Dog Fashion Disco
The Doors
Dr. Octagon
Drudkh
Duster
Edge of Sanity
Elbow
Elder
Electric Wizard
Elliott Smith
Emerson, Lake & Palmer
Failure
Fall Out Boy
Fates Warning
Fear Factory
Fennesz
Fever Ray
Fiona Apple
The Flaming Lips
Flying Lotus
Frank Ocean
Frank Zappa
Gas
Genesis
Gentle Giant
Godspeed You! Black Emperor
Gojira
Gorguts
Gorillaz
Grimes
Guided by Voices
Haken
Have a Nice Life
iamthemorning
Intronaut
ISIS
J Dilla
James Blake
James Ferraro
Jane's Addiction
Janelle Monae
Japan
Jeff Rosenstock
Jefferson Airplane
Jethro Tull
Jim O'Rourke
The Jimi Hendrix Experience
John Cale
Jon Hopkins
Joy Division
Julia Holter
Justice
Kanye West
Kashiwa Daisuke
Kate Bush
Kayo Dot
Kendrick Lamar
King Crimson
Klaxons
The Knife
Kraftwerk
Kyuss
La Dispute
Laurel Halo
Laurie Anderson
Lou Reed
Low
Luomo
Mac DeMarco
Madvillain
The Mars Volta
Marvin Gaye
Massive Attack
Mastodon
maudlin of the Well
Melvins
Mercury Rev
Meshuggah
MF Doom
The Microphones
Miles Davis
Misfits
Modest Mouse
Morbid Angel
Muse
My Bloody Valentine
My Chemical Romance
Nas
The National
Ne Obliviscaris
Neu!
Neurosis
Neutral Milk Hotel
Nick Drake
Nine Inch Nails
No-Man
The Notorious B.I.G.
Novembre
Oceansize
The Olivia Tremor Control
Opeth
Orbital
Pain of Salvation
Paramore
Paul McCartney
Pearl Jam
Peter Gabriel
Pink Floyd
Porcupine Tree
Portishead
Protest the Hero
Public Enemy
Queens of the Stone Age
Radiohead
Raekwon
Red House Painters
The Residents
Ride
The Rolling Stones
The Roots
Royksopp
Rush
School Food Punishment
Scott Walker
Sheena Ringo
Shugo Tokumaru
Sigh
Sigur Ros
Silversun Pickups
Sleep
Sleepytime Gorilla Museum
Slowdive
Smashing Pumpkins
The Smiths
Snowing
Sonic Youth
Sparks
Spiritualized
Squarepusher
St. Vincent
Stereolab
Steven Wilson
Stevie Wonder
Strapping Young Lad
The Strokes
Sufjan Stevens
Supertramp
Sweet Trip
Syd Barrett
Talk Talk
Talking Heads
Tame Impala
The The
Throbbing Gristle
Tool
Tori Amos
TV on the Radio
Ulver
UNKLE
Unwound
Uriah Heep
Van Dyke Park
Vektor
Venetian Snares
The Velvet Underground
Voivod
The Who
Wilco
Wu-Tang Clan
Xiu Xiu
Yes
Yo La Tengo