Question: This Is Spinal Tap co-starred which actor known for his voice work on The Simpsons?

Context paragraphs:
Nigel Tufnel: Nigel Tufnel is a fictional character in the 1984 mockumentary film "This Is Spinal Tap".  In the film, he is the lead guitarist of the rock band Spinal Tap.  He was played by actor Christopher Guest.

Robert Leighton (film editor): Robert Leighton is a British film and television editor with more than 30 feature film credits since 1980.  He has edited nearly all of the films by film director Rob Reiner, commencing with "This is Spinal Tap" in 1984.  He has also edited three films with Christopher Guest.  His work includes hit comedies and mockumentaries such as "This is Spinal Tap", "Best in Show" and "When Harry Met Sally" as well as classic dramas such as "Stand by Me" and the Stephen King thriller, "Misery", which garnered actress Kathy Bates a "Best Actress" Oscar.  He was nominated for the Academy Award for Best Film Editing for the feature film, "A Few Good Men" (1992).

This Is Spinal Tap (album): This Is Spinal Tap (or simply Spinal Tap) was the soundtrack to the film "This Is Spinal Tap", released in 1984.  It was re-released in 2000 with lyrics and two versions of "Christmas with the Devil" as bonus tracks.  The cover art is identical to that of the fictional album "Smell the Glove" featured in the film.

Harry Shearer: Harry Julius Shearer (born December 23, 1943) is an American actor, voice actor, comedian, writer, musician, author, radio host, director and producer.  He is known for his long-running roles on "The Simpsons", his work on "Saturday Night Live", the comedy band Spinal Tap and his radio program "Le Show".  Born in Los Angeles, California, Shearer began his career as a child actor.  From 1969 to 1976, Shearer was a member of The Credibility Gap, a radio comedy group.  Following the breakup of the group, Shearer co-wrote the film "Real Life" with Albert Brooks and started writing for Martin Mull's television series "Fernwood 2 Night".

Spinal Tap (band): Spinal Tap (stylized as Spın̈al Tap, with a dotless letter "i" and a metal umlaut over the "n") is a parody band spoofing the style of rock heavy metal groups.  The band first appeared on a 1979 ABC TV sketch comedy pilot called "The T.V. Show", starring Rob Reiner.  The sketch, actually a mock promotional video for the song "Rock and Roll Nightmare", was written by Reiner and the band, and included songwriter/performer Loudon Wainwright III on keyboards.  Later the band became the fictional subject of the 1984 rockumentary/mockumentary film "This Is Spinal Tap".  The band members are portrayed by Michael McKean (as David St. Hubbins), Christopher Guest (as Nigel Tufnel) and Harry Shearer (as Derek Smalls).

Spontaneous Combustion (album): Spontaneous Combustion is an album by progressive metal group Liquid Trio Experiment, and is the result of the studio improvisations of Liquid Tension Experiment which occurred while John Petrucci was with his wife while she was giving birth.  The trio of Mike Portnoy, Tony Levin and Jordan Rudess continued to write music during this period.  It was released on October 23, 2007.  A few songs from "Liquid Tension Experiment 2" were spawned from these jam sessions including "914", "Chewbacca", and "Liquid Dreams".  The song "Chris & Kevin's Bogus Journey" is not a reference to Portnoy and Petrucci's former Dream Theater bandmates Chris Collins and Kevin Moore, but rather to the track on Liquid Tension Experiment's first album entitled "Chris & Kevin's Excellent Adventure", which is itself a reference to the band's photographer's habit of calling Mike Portnoy and Tony Levin "Chris and Kevin", even after being corrected several times.  It is also a reference to the 1991 film "Bill & Ted's Bogus Journey", the sequel to "Bill & Ted's Excellent Adventure".  The song "Jazz Odyssey" is a reference to the movie "This Is Spinal Tap", in which Spinal Tap experiments with an improvisational song of the same name.

David St. Hubbins: David Ivor St. Hubbins is a fictional character in the mockumentary film "This Is Spinal Tap" (1984).  In the film, he is the lead singer and rhythm guitarist of the mock rock band Spinal Tap.  David is played by actor Michael McKean, who improvised the role through the whole film.  McKean writes in his introduction to "This Is Spinal Tap: The Official Guide", "When I am called upon to generate copy about the mostly fictional entity called Spinal Tap, I usually do so in the mostly fictional character of David St. Hubbins..."

This Is Spinal Tap: This Is Spinal Tap (stylized as This Is Spın̈al Tap) is a 1984 American rock music mockumentary comedy film directed, co-written, scored by, and starring Rob Reiner, and co-starring Christopher Guest, Michael McKean and Harry Shearer.  The film portrays the fictional British heavy metal band Spinal Tap.  The film satirizes the wild personal behavior and musical pretensions of hard rock and heavy metal bands, as well as the hagiographic tendencies of rock documentaries of the time.  The three main members of Spinal Tap—David St. Hubbins, Derek Smalls and Nigel Tufnel—are played by actors McKean, Shearer, and Guest, respectively.  The three actors play their musical instruments and speak with mock English accents throughout the movie.  Reiner appears as Marty Di Bergi, the maker of the documentary.  Other actors in the movie are Tony Hendra as group manager Ian Faith, and June Chadwick as St. Hubbins' interfering girlfriend Jeanine.  Actors Paul Shaffer, Fred Willard, Fran Drescher, Bruno Kirby, Howard Hesseman, Ed Begley, Jr., Patrick Macnee, Anjelica Huston, Vicki Blue, Dana Carvey, Billy Crystal and Linnea Quigley all play supporting roles or make cameo appearances in the movie.

Michael McKean: Michael John McKean (born October 17, 1947) is an American actor, comedian, and musician, known for a variety of roles played since the 1970s.  He first came to national attention playing annoying neighbor Lenny Kosnowski on the sitcom "Laverne & Shirley".  In the mid-1990s he was a repertory cast member of "Saturday Night Live".  He has played roles in several Christopher Guest ensemble films, particularly as David St. Hubbins, lead vocalist and rhythm guitarist of the fictional rock band Spinal Tap in "This Is Spinal Tap".  He co-wrote the song "A Mighty Wind" (from the film of the same name), which won a Grammy Award, as well as "A Kiss at the End of the Rainbow" from the same film, which was nominated for the Academy Award for Best Song.  He plays Chuck McGill, brother of the protagonist of the AMC drama "Better Call Saul".

Back from the Dead (Spinal Tap album): Back from the Dead is the third studio album by Spinal Tap, though it is the fourteenth when including their fictional albums.  Released on June 16, 2009, it is the first release under the Spinal Tap name since 1992's "Break Like the Wind".

Supporting paragraphs: This Is Spinal Tap Harry Shearer
Answer: Harry Julius Shearer