Season 20

Whitney Cummings, Nicole

Tracy Morgan, Rick & Corey Harrison, Shaggy

Michelle Williams, Josh Lucas, Chris Cornell

Glenn Close, Trevor Noah, Van Hunt

Janet Jackson, Larry the Cable Guy, Eli Young Band

Queen Latifah, Paul

Liam Neeson, Jack's Mannequin

Gerard Butler, Betty White

Tilda Swinton, Jennifer Hudson, Graffiti6

Sam Worthington, Sherri Shepherd, Adam Lambert

Jennifer Garner, Ross Matthews, Parachute

Wanda Sykes

Steven Tyler, Ryan Seacrest, Randy Jackson, Sarah Colonna

Madonna, Chris Colfer, Joe Perry

Michelle Obama, Mark Harmon, Imelda May

Daniel Radcliffe, Vanessa Hudgens, Evanescence

Drew Barrymore, Blake Shelton

Debra Messing, Jean Dujardin, Bush

Dwayne Johnson, Miranda Cosgrove, Cirque du Soleil

Chelsea Handler, Jon Huntsman, 2Cellos

Chris Pine, Lisa Lampanelli, Anthony Hamilton

Denzel Washington, Octavia Spencer, Estelle

Rachel McAdams, Cee-Lo Green

Jennifer Lopez, the Civil Wars

Tyler Perry, Alexandra Wentworth, the Cranberries

Bill Maher, Punch Brothers

Amanda Seyfried, Billy Gardell, Monica, Brandy

Christina Aguilera, Dave Salmoni, The Fray

Taylor Swift, Michael Clarke Duncan, Robert Randolph, Los Lobos, Chris Layton

Bill O'Reilly, Rob Riggle, Rumer

Tim Allen, Rocket City Rednecks

Meredith Vieira, Jackson Murphy

Jennifer Aniston, Adam Levine

Megan Fox, Michel Hazanavicius, Mariachi El Bronx

Rob Schneider, Khloe Kardashian Odom, Mona

Sen. John McCain, Elizabeth Olsen, Romeo Santos

Julianne Moore, Dr. Brady Barr, Chickenfoot

Emily Blunt, Geoff Stults, Scars on 45

Jessica Simpson, Adam Carolla, Soja

Jonah Hill, Bethenny Frankel, Shooter Jennings

Channing Tatum, Drew Brees, Meat Loaf

Kiefer Sutherland, Kathryn Hahn, Andy Grammer

Jimmy Fallon, 8-year-old presidential whiz kid H.L. McCullough, Toby Keith

Jamie Lee Curtis, Armie Hammer

Rep. Ron Paul, Frank Caliendo, the Wanted

Kim Kardashian

Arsenio Hall, Lily Collins

Christina Aguilera, Melanie Fiona featuring J. Cole

Elizabeth Banks, Carson Daly

The Pierces

Rainn Wilson, Debbie Gibson, Gavin DeGraw

Piers Morgan, Liam Hemsworth, Mat Kearney

Nicole Richie, Alan Jackson

Betty White, D.J. Pauly D

Maya Rudolph, Jason Biggs, Gym Class Heroes

David Gregory, Cee-Lo Green, Seal

Zac Efron, Jennie Garth, Grace Potter and the Nocturnals

Kristin Chenoweth, Julie Scardina, Rodrigo y Gabriela

Jane Lynch, Kevin Hart, Esperanza Spalding

Josh Hutcherson, Rachel Maddow, Eric Turner featuring Lupe Fiasco and Tinie Tempah

Albert Brooks, Austin

Blake Shelton, Chris Diamantopoulos, Feist

Jason Segel, Anna Faris, Far East Movement

Jesse Tyler Ferguson, Aubrey O'Day, Train

Jack Black, Daniel Holzman & Michael Chernow, Beirut

Adam Levine, Ziggy Marley

Diane Keaton, Natalie Coughlin, Moby

Mel Gibson, the Wanted

Steve Martin, Rashida Jones, Steve Martin & the Steep Canyon Rangers

Cameron Diaz, William Shatner, Lee Brice

Scarlett Johansson, Blake Shelton, K'Naan featuring Nelly Furtado

Robert Downey Jr., Katharine McPhee, Toast To Freedom

Kristen Stewart, James Morrison

Michelle Pfeiffer, Bear Grylls, Snow Patrol

Rick Santorum, Taylor Kitsch, B.o.B., O.A.R.

Garry Shandling, Alison Brie, the winner of 'The Voice'

Howie Mandel, Vinny Guadagnino, Sara Watkins

Jenna Fischer, Jay Mohr

Kourtney, Kim & Khloe Kardashian, Donny Deutsch, Karmin

Wanda Sykes, David Hasselhoff, Santana

Joel McHale, Jarod Miller, Bobby Brown

Hugh Laurie, Robert Griffin III

Sherri Shepherd, Julianne Hough, Tenacious D

Kevin Costner, Bailee Madison, Lisa Marie Presley

Josh Brolin, Ali Wentworth, Glenn Frey

Charlize Theron, Jeffrey Dean Morgan, Juanes

Glenn Close, the winner of American Idol, Nelly Furtado

Gen. Colin Powell, Greg Gadson, All American Rejects

Martin Short, Aubrey Plaza, Def Leppard

Emma Stone, Chris Hemsworth, Chris Robinson Brotherhood

Julia Louis-Dreyfus, the Beach Boys

Catherine Zeta-Jones, Louis Zamperini, Bret Michaels

Tom Cruise, skydivers Felix Baumgartner & Joe Kittinger, Kool & the Gang

Elizabeth Banks, Dan Patrick, Brandi Carlisle

Patrick Duffy, Linda Grey, Larry Hagman, Meghan McCain, Meiko

Terry Bradshaw, Ernie Brown Jr., Neal James, Rachel Bradshaw

Penelope Cruz, Rick Harrison, We Are Augustines

Salma Hayek, Adam Brody, Olly Murs

Steve Carell, Cory Booker, Glen Hansard

Matthew McConaughey, Natasha Leggero, Grouplove

Andy Samberg, Seth MacFarlane, Joe Henry featuring Lisa Hannigan

Katy Perry, Needtobreathe

Chris Pine, Rachael Ray, Everclear

Louis C.K., Lolo Jones, Delta Rae

Matt LeBlanc, Sig Hansen & Keith Colburn, Robin Thicke

Mila Kunis, Jim Norton, Justin Bieber

Tyler Perry, Rhys Ifans, Keane

Andrew Garfield, Of Monsters And Men

Wanda Sykes, Rob Riggle, Kimbra

Zachary Levi, B.o.B.

Morgan Freeman,

Denis Leary, Olivia Munn, Kenny Chesney

Dana Carvey, Nicki Minaj

Charlie Sheen

Kate Beckinsale, Adam Carolla

Newt Gingrich, Nicole

Rachel Weisz, Aaron Paul

Ben Stiller, Rose Byrne, Missy Higgins

Vince Vaughn, Travis Pastrana, Aretha Franklin

Colin Farrell, Jenni

Jessica Biel, Kevin Smith, the Lumineers

Julie Scardina, Dwyane Wade, MoZella

Jeremy Renner, Betty White, Joss Stone

Michelle Obama, Norah Jones

Kelsey Grammer, Jordan Burroughs, Ryan Star

Sylvester Stallone, Missy Franklin, Dwight Yoakam

Kristen Bell, Ryan Lochte, Regina Spektor

Jason Statham, Allyson Felix, the Offspring

Maya Rudolph, Jeff Foxworthy, Morning Parade

Shia LaBeouf, Jean-Claude Van Damme, fun.

Katie Couric, Dax Shepard, Emeli Sande

Kirsten Dunst, Chris Matthews, Smashing Pumpkins

Howie Mandel, Alejandro Escovedo

Dennis Miller, Joshua Radin

Owl City with Carly Rae Jepsen

Bill Maher, Tristan Prettyman

Savannah Guthrie, Dolph Lundgren

Lauren Graham, Dan Patrick

Kevin Hart, Rep. Ron Paul, Robert Cray

Adam Levine, Magic Johnson, Grace Potter

Ellen DeGeneres, Josh Lucas, Billy Ray Cyrus

Matthew Perry, Meghan McCain, OneRepublic

Richard Gere, Anthony Robles, Rascal Flatts

Justin Timberlake, Steve Nash, Ryan Bingham

Amy Poehler, Joe Scarborough, Big & Rich

Viola Davis, Paul Wesley, Bonnie Raitt

Zooey Deschanel, Anthony Anderson, ZZ Top

David Spade, Giancarlo Esposito, Rebecca Ferguson

Ann Romney, Seth MacFarlane, Bettye LaVette

Kirstie Alley, Mike

Liam Neeson, Lisa Lampanelli, the Gaslight Anthem

Christina Aguilera, Sherri Shepherd, the Piano Guys

Bryan Cranston, Rebel Wilson, Cher Lloyd

Carol Burnett, Armie Hammer, Lang Lang

Christina Applegate, Apolo Anton Ohno

Ben Affleck, Octavia Spencer, Neon Trees

Colin Farrell, Medal of Honor recipient Dakota Meyer, the Hives

Arnold Schwarzenegger, Bubba Watson, the Wallflowers

Tyler Perry, Oscar Pistorius, Plain White T's

Chelsea Handler, Placido Domingo

Terry Bradshaw, Mark Kelly, Grizzly Bear

Whitney Cummings, Rove McManus, the Script

Halle Berry, Ali Wentworth, Gary Clark Jr.

Denzel Washington, Richard Engel, M. Ward

President Barack Obama, No Doubt

Russell Brand, Jane Lynch

Sarah Silverman, Paula Deen

Simon Cowell, Britney Spears, Billy Gardell, Two Door Cinema Club

John C. Reilly, Jenni

Taylor Lautner, Lior Suchard, Macy Gray

Jamie Lee Curtis, Maggie Elizabeth Jones, ZZ Ward

Marion Cotillard, Olate Dogs

Kristen Stewart, Dax Shepard, Kip Moore

Daniel Craig, Dave Salmoni, Diamond Rings

Sally Field, Chris Matthews, Lord Huron

Meredith Vieira & Richard Cohen, Christina Perri

Lea Michele, Nev Schulman, Toby Keith

Keira Knightley, Whitney Cummings, Gin Wigmore

Helen Hunt, Paul

Tim Allen, Nolan Gould, Switchfoot

Chris Matthews, the Mowgli's

Jennifer Lawrence, Phil & Willie Robertson, Andy Grammer

Oscar-nominated actress Jennifer Lawrence; from “Duck Dynasty”, Phil & Willie Robertson; music from Andy Grammer.

Lindsay Lohan, David Gregory, Wanda Jackson

Joseph Gordon-Levitt, Kris Jenner, Dan Cummings

Bradley Cooper, Natasha Leggero, PSY

Jim Parsons, Maggie Elizabeth Jones, Delta Rae

Julie Bowen,

Wanda Sykes, Blake Shelton

Newt Gingrich, Ron Shirley, Grouplove

Marisa Tomei, Carson Daly, Il Volo

Gerard Butler, Olivia Munn, the Polyphonic Spree

Khloe Kardashian Odom, Adam Carolla, Matisyahu

Don Johnson, Julie Scardina, Darius Rucker

Bill O'Reilly, Krysten Ritter, Paloma Faith

Leslie Mann, Jim Rome, Garbage

Matt Damon, Chris Pratt, Of Monsters And Men

Ewan McGregor, Bailee Madison, Allen Stone

Albert Brooks, Kerry Washington, Willy Moon

Hugh Jackman, Maria Sharapova, J.D. McPherson

From "Les Misérables", Actor Hugh Jackman; magician Justin Willman; music act JD McPherson. Maria Sharapova preempted.

Bette Midler, Judd Apatow, Pentatonix

Megan Fox, Johnny Manziel, Colbie Caillat

Quentin Tarantino, LeAnn Rimes

Jamie Foxx, Carl Reiner, the winner of

Katherine Heigl, Marjorie Johnson, Johnny Mathis

Terry Bradshaw, Elle Fanning, Chris Mann