Paul McCartney

Paul. You can generally answer this question by identifying the singer -- almost always, the lead singer was also the author. John and Paul agreed to share credits on all of their songs early on, which makes it hard to tell just by reading the liner notes.

Of The Beatles, Paul McCartney wrote it. He was inspired by his mother. He refers to her in the song as, "Mother Mary".

Paul did.

Paul McCartney.

1) "Let It Be" is a song written by Paul McCartney (credited to Lennon/McCartney), released by The Beatles as a single in March 1970 and later the same year as the title track of their album Let It Be. The single reached #1 in the U.S. and #2 in the UK. In 2004, it was ranked number 20 on Rolling Stone magazine's list of the 500 greatest songs of all time." "McCartney said he wrote "Let It Be", inspired by a dream he had during the tense period surrounding the Get Back/Let It Be sessions. He dreamt of his mother, and the "Mother Mary" lyric refers to her (Mary (Mohin) McCartney). She died of cancer when McCartney was 14. He said, "It was great to visit with her again. I felt very blessed to have that dream. So that got me writing 'Let It Be'."" "John Lennon was not fond of "Let It Be." Prior to a take during the 31 January 1969 recording session, he asked, "Are we supposed to giggle in the solo?" In his 1980 Playboy interview, he disavowed any involvement with composing the song. He said, "That's Paul. What can you say? Nothing to do with the Beatles. It could've been Wings. I think it was inspired by "Bridge Over Troubled Waters." That's my feeling, although I have nothing to go on. I know he wanted to write a "Bridge Over Troubled Waters."" Source and further information: http://en.wikipedia.org/wiki/Let_It_Be_%28song%29 2) ""Let It Be" is a song written by Lennon & McCartney (although thought to be the sole work of Paul McCartney). The song was first recorded by The Beatles and released as a single in March 1970 and later the same year as the title track of their acclaimed album Let It Be." Source: http://www.youtube.com/watch?v=67J_66hdN-I 3) So either did John Lennon not work on the song or he would rather not have been involved in composing it...

paul wrote it john and george helped with the music

I'm guessing here, but just from the style and the singer, it's gotta be Paul.