Question: Who voiced the title character in a 30-minuted animated film based on a song written by Leonard Lipton and Peter Yarrow?

full_context: Document 1: Peter Pan (1976 musical): Peter Pan is a 1976 musical adaptation of J. M. Barrie's "Peter Pan, or the Boy Who Wouldn't Grow Up", produced for television as part of the "Hallmark Hall of Fame", starring Mia Farrow as Peter Pan and Danny Kaye as Captain Hook, and with Sir John Gielgud narrating. Julie Andrews sang one of the songs, "Once Upon a Bedtime", off-camera over the opening credits. It aired on NBC at 7:30pm on Sunday, December 12, 1976, capping off the program's 25th year on the air. The program did not use the score written for the highly successful Mary Martin version which had previously been televised many times on NBC. Instead, it featured 14 new and now forgotten songs, written for the production by Anthony Newley and Leslie Bricusse. The story was adapted by Andrew Birkin (who would subsequently become a leading Barrie scholar) and Jack Burns. Although it was an American production with two American stars, most of the cast was British.
Document 2: Frosty the Snowman (film): Frosty the Snowman is a 1969 animated Christmas television special based on the song "Frosty the Snowman". The program, which first aired on December 7, 1969 on CBS (where it still airs to this day), was produced for television by Rankin/Bass Productions and featured the voices of comedians Jimmy Durante as the film's narrator (Durante's final performance in a film) and Jackie Vernon as the title character.
Document 3: Thurl Ravenscroft: Thurl Arthur Ravenscroft ( ; February 6, 1914May 22, 2005) was an American voice actor and bass singer known as the booming voice behind Tony the Tiger's "They're grrreat!" in Kellogg's Frosted Flakes television commercials for more than five decades. Ravenscroft was also known, albeit uncredited, as the vocalist for the song "You're a Mean One, Mr. Grinch" from the classic Christmas television special, Dr. Seuss' "How the Grinch Stole Christmas!"
Document 4: Peter Yarrow: Peter Yarrow (born May 31, 1938) is an American singer and songwriter who found fame with the 1960s folk music trio Peter, Paul and Mary. Yarrow co-wrote (with Leonard Lipton) one of the group's greatest hits, "Puff, the Magic Dragon". He is also a political activist and has supported causes that range from opposition to the Vietnam War to the creation of Operation Respect, an organization that promotes tolerance and civility in schools.
Document 5: Puff, the Magic Dragon: "Puff, the Magic Dragon" (or "Puff") is a song written by Leonard Lipton and Peter Yarrow, and made popular by Yarrow's group Peter, Paul and Mary in a 1963 recording.
Document 6: Pete's Dragon (2016 film): Pete's Dragon is a 2016 American fantasy comedy-drama adventure film directed by David Lowery, written by Lowery and Toby Halbrooks, and produced by James Whitaker. The film is a reboot of the 1977 musical film of the same name written by Malcolm Marmorstein. The film stars Bryce Dallas Howard, Oakes Fegley, Wes Bentley, Karl Urban, Oona Laurence, and Robert Redford. The film tells the story of an orphaned feral boy who befriends a dragon in the Pacific Northwest, and the ensuing repercussions of their discovery by the town's local residents.
Document 7: Lucy in the Sky with Diamonds: "Lucy in the Sky with Diamonds" is a song credited to Lennon–McCartney that appears on the Beatles' 1967 album "Sgt. Pepper's Lonely Hearts Club Band". It was started by John Lennon, then Paul McCartney contributed to it in a songwriting session. Lennon's son Julian inspired the song with a nursery school drawing he called "Lucy—in the sky with diamonds". Shortly after the song's release, speculation arose that the first letter of each of the title nouns intentionally spelled "LSD". Lennon consistently denied this, insisting the song's fantastical imagery was inspired by Lewis Carroll's "Alice in Wonderland" books, a claim repeatedly confirmed by Paul McCartney.
Document 8: The Spectrum Song: "The Spectrum Song" was written by the Sherman Brothers in 1961 under assignment from Walt Disney to be a signature song for the fictional character Ludwig Von Drake. Nominally about different colors in the spectrum, the song's lyrics initially consist of the repeated color names red, yellow, green and blue, but soon veer wildly off into cerise, chartreuse, ultramarine and plaid.
Document 9: Day Is Done (Peter, Paul and Mary song): "Day Is Done" is a song written by Peter Yarrow. It was recorded by Yarrow's group Peter, Paul and Mary and released as a single in 1969. The song reached No. 21 on "Billboard" Hot 100, and was ranked No. 48 on the "Billboard" year-end Top Easy Listening Singles chart of 1969.
Document 10: Puff the Magic Dragon (film): Puff the Magic Dragon is a 30-minute animated television film based on the song of the same name by Peter, Paul and Mary. The title character was voiced by Burgess Meredith. The doctors were voiced by Frank Nelson, Regis Cordic, and Charles Woolf. The special first aired October 30, 1978 on CBS.
Document 11: Who's Afraid of the Big Bad Wolf?: "Who's Afraid of the Big Bad Wolf" is a popular song written by Frank Churchill with additional lyrics by Ann Ronell, which originally featured in the 1933 Disney cartoon "Three Little Pigs", where it was sung by Fiddler Pig and Fifer Pig (voiced by Mary Moder and Dorothy Compton) as they arrogantly believe their houses of straw and twigs will protect them from the Big Bad Wolf (voiced by Billy Bletcher). The song's theme made it a huge hit during the 1930s and it remains one of the most well-known Disney songs, being covered by numerous artists and musical groups. Additionally, it was the inspiration for the title of Edward Albee's 1963 play "Who's Afraid of Virginia Woolf?"
Document 12: Mowgli's Brothers (TV special): Mowgli's Brothers is a 1976 television animated special directed by American animator Chuck Jones. It is based on the first chapter of Rudyard Kipling's "The Jungle Book". The special was narrated by Roddy McDowall, who also performs the voices of all the male characters in the film. June Foray was the voice of Raksha, the Mother Wolf. It originally aired on CBS on February 11, 1976. The special was released on VHS, Betamax, and Laserdisc by Family Home Entertainment in 1985, and it was released on VHS again on VHS in 1999 and on DVD in 2002 and 2007 by Lionsgate. Jones also directed adaptations of two other "The Jungle Book" stories, "Rikki-Tikki-Tavi" and "The White Seal", in 1975.
Document 13: The Smurfs in film: The Smurfs have appeared in three feature-length films and two short films loosely based on "The Smurfs" comic book series created by the Belgian comics artist Peyo and the 1980s animated TV series it spawned. The 2011 feature film of the same name and its 2013 sequel were produced by Sony Pictures Animation and released by Columbia Pictures. Live-action roles include Hank Azaria and Neil Patrick Harris, while the voice-over roles include Anton Yelchin, Jonathan Winters, Katy Perry, and George Lopez. A fully animated reboot titled "" was scheduled for release through Sony in April 2017.
Document 14: Puff and the Incredible Mr. Nobody: Puff and the Incredible Mr. Nobody is a 30-minute animated television film loosely based on the song "Puff, the Magic Dragon" by Leonard Lipton and Peter Yarrow. The title character was voiced by Burgess Meredith, and the film also featured the voice of David Mendenhall. The special first aired May 17, 1982 on CBS. This was the last "Puff the Magic Dragon" special.
Document 15: Fred Wolf Films: Fred Wolf Films is an American animation studio founded in the 1960s by Fred Wolf and Jimmy Murakami (the latter of whom worked on the TV special "The Snowman"). It was founded as MW (Murakami-Wolf). The studio produced "The Point", the first U.S. animated special to air in prime time (on the ABC network in 1971). It was also responsible for "Free to Be… You and Me", the "Puff the Magic Dragon" specials, and television series such as "Teenage Mutant Ninja Turtles", "Toxic Crusaders", "Alvin and The Chipmunks" (eleven episodes from the sixth season), "James Bond Jr.", "The New Adventures of Speed Racer", and Sarah Ferguson's "Budgie the Little Helicopter".
ground_truth: Burgess Meredith