<P> Schaal has also performed at the Royal Albert Hall, London, as part of The Secret Policeman's Ball 2008 in aid of Amnesty International, and at the Bonnaroo 2009 music festival . In 2010, Schaal appeared as a stand - up comic on John Oliver's New York Stand Up Show and at the Solid Sound Festival at the Massachusetts Museum of Contemporary Art . </P> <P> Schaal appeared on HBO's Flight of the Conchords as the stalker - fan Mel, a role which earned her an EWwy nomination for Best Supporting Actress in a Comedy Series in 2009 . She was also a credited consultant and writer for Season 11 of South Park, appeared on the BBC's Never Mind the Buzzcocks and played the boss in Fuse's mockumentary The Intern . She made her first appearance as a "special commentator" on Comedy Central's The Daily Show on March 13, 2008, often presented in recurring appearances as its news team's "Senior Women's Issues Correspondent". On April 13, 2008, she made an appearance on Good News Week during the Melbourne International Comedy Festival and in October 2008 she appeared in Amnesty International's The Secret Policeman's Ball 2008 . </P> <P> Her other film and television credits include Kate and Leopold, Aqua Teen Hunger Force, Snake' n' Bacon, Norbit, Get Him to the Greek, Conviction, Cheap Seats, Freak Show, Cirque du Freak: The Vampire's Assistant, Adam and Steve, The Goods: Live Hard, Sell Hard, Delirious, Australian show Good News Week, Law & Order: Special Victims Unit, Law & Order: Criminal Intent, The Education of Max Bickford, Comedy Central's Contest Searchlight, Ugly Betty, How I Met Your Mother, MTV's Human Giant and Mad Men . She was also a contributor to the sketch / music series The Nighttime Clap on the Fuse music network . She also appeared on Fuse's original comedy series The P.A. Schaal appeared in two TV pilots written and directed by Jersey City comedian Dan McNamara--The Calderons and Redeeming Rainbow, both of which were screened as official selections at the 2006 and 2007 New York Television Festivals . She was also in television commercials for Wendy's, RadioShack, and Starburst . She made an appearance, in April 2008, on the IFC sketch comedy show The Whitest Kids U' Know . On April 3, 2009 she taped an episode of Comedy Central Presents . In 2010, she added her voice to the PBS Kids GO! series WordGirl as Victoria Best, a child prodigy whose parents taught her to be the best at everything that she does . Schaal voiced 13 - year - old Mabel Pines on Disney Channel's hit TV series Gravity Falls . She currently voices the character Louise on the FOX Network series Bob's Burgers . </P> <P> She also stars in A.D. Miles' MyDamnChannel.com series Horrible People . In October 2008, Schaal appeared in an episode of Spicks and Specks . On June 10, 2009, Schaal broadcast her first radio show, High Five!!, on Sirius XM Radio's' RawDog' channel with co-host Kurt Braunohler . She played Gertha Teeth in the 2009 movie The Vampire's Assistant . Schaal stars in her own web series, Penelope Princess of Pets, one episode of which doubled as the video for the New Pornographers' "Mutiny, I Promise You". She voiced Trixie the Triceratops in Toy Story 3 and Pumpkin Witch and Palace Witch in Shrek Forever After . She was also in the music video for Joey Ramone's "New York City". She also guest starred in the Modern Family episode "Fifteen Percent", as well as the music video for "Conversation 16" by The National . Schaal guest starred on the MC Frontalot album Solved . She was featured with Kurt Braunohler on the Radiolab episode "Loops". Schaal was in a commercial for the Xperia Play version of Minecraft . </P>

Who plays the voice of mabel in gravity falls