Question: Which director, Piers Haggard or Penelope Spheeris, is best known as a documentary film director whose works include the trilogy titled "The Decline of Western Civilization"?

Context paragraphs:
The Fiendish Plot of Dr. Fu Manchu: The Fiendish Plot of Dr. Fu Manchu is a 1980 comedy film, primarily notable as the final film of Peter Sellers, David Tomlinson and John Le Mesurier.  Pre-production began with Richard Quine as director.  By the time the film entered production, Piers Haggard had replaced him.  Peter Sellers handled the re-shoots himself.  Based on characters created by Sax Rohmer, the film stars Sellers in the dual role of Fu Manchu, a stereotypical Chinese evil genius, and English country gentleman detective Nayland Smith.  Released only two weeks after Sellers death, the film was a commercial and critical failure.  It was also the final screen appearance for Tomlinson, who retired from acting shortly before its release.

Germs (band): The Germs were an American punk rock band from Los Angeles, California, United States, originally active from 1977 to 1980.  The band's main early lineup consisted of singer Darby Crash, guitarist Pat Smear, bassist Lorna Doom and drummer Don Bolles.  They released only one album, 1979's "(GI)", produced by Joan Jett, and were featured the following year in Penelope Spheeris' documentary film "The Decline of Western Civilization", which chronicled the Los Angeles punk movement.

Uncle Tom's Fairy Tales: Uncle Tom's Fairy Tales: The Movie for Homosexuals is a 1968 film directed by then-film student Penelope Spheeris (later the director of "The Decline of Western Civilization" and its two sequels), starring comedian Richard Pryor.  The only known negative of the film was said to have been shredded by Pryor after a disagreement with his wife at the time.

Piers Haggard: Piers Inigo Haggard OBE (born 18 March 1939) is a British theatre, film and television director, although he has worked mostly in the latter.

Matthew Felker: Matthew Felker is an American writer, producer, actor, and model.  He is currently starring and an executive producer on the Penelope Spheeris directed comedy titled "Balls to the Wall" opposite Mimi Rogers, Christopher McDonald, Joe Hursley, Colleen Camp and Jenna Dewan.  He works often with directors Penelope Spheeris and Joseph Kahn.

Penelope Spheeris: Penelope Spheeris (born December 2, 1945 or 1946; sources differ) is an American film director, producer and screenwriter.  She is best known as a documentary film director whose works include the trilogy titled "The Decline of Western Civilization".  She has directed feature films, including "Wayne's World", her highest-grossing film.

The Decline of Western Civilization: The Decline of Western Civilization is an American documentary film filmed through 1979 and 1980.  The movie is about the Los Angeles punk rock scene and was directed by Penelope Spheeris.  In 1981, the LAPD Chief of Police Daryl Gates wrote a letter demanding the film not be shown again in L.A.

A Summer Story: A Summer Story is a British drama film released in 1988.  Directed by Piers Haggard, with a script written by Penelope Mortimer.  It stars James Wilby, Imogen Stubbs, and Susannah York.  In 1904, a young gentleman visiting a rural area has an intense love affair with a village girl.  Eighteen years later, he is passing that way again.  The film is based on the John Galsworthy story "The Apple Tree".

Warren Lewis (screenwriter): Warren Lewis is an American film producer and screenwriter.  He is best known for his screenwriting contributions on the films "Black Rain" (1989, directed by Ridley Scott) and "The 13th Warrior" (1999, directed by John McTiernan).  He also worked as an assistant film director on numerous studio and independent films, including Boaz Davidson's "Hospital Massacre" (1982), Penelope Spheeris' "The Boys Next Door" (1985) and McTiernan's directorial debut film "Nomads" (1986).  Lewis has an extensive background in film and video production.

The Decline of Western Civilization III: The Decline of Western Civilization III is a 1998 documentary film directed by Penelope Spheeris that chronicles the gutter punk lifestyle of homeless teenagers.  It is the third film of a trilogy by Spheeris depicting life in Los Angeles at various points in time.  The first film "The Decline of Western Civilization" dealt with the punk rock scene during 1980-1981.  The second film "" covers the Los Angeles heavy metal movement of 1986-1988.

Supporting paragraphs: Piers Haggard Penelope Spheeris
Answer: Penelope Spheeris