Gary Trust of Billboard's Chart Beat published the lists of
songwriters and
producers with the most Hot 100 No. 1s, in April 2011. This is an
updated version of both lists.
Songwriters with the most #1s
Paul McCartney (32)
John Lennon (26)
Mariah Carey (17)
Barry Gibb (16)
Brian Holland (15)
Sean Garrett (15)
Max Martin (15)
Producers with the most #1s
George Martin (23)
Jimmy Jam (16)
Terry Lewis (16)
Steve Sholes (16)
Barry Gibb (14)
Mariah Carey (14)
#1s as a Songwriter (Paul McCartney, John Lennon, Mariah Carey, Max Martin)
Paul McCartney
Solo, Lead (3): "Uncle Albert/Admiral Halsey", "Ebony and Ivory" (Stevie Wonder), "Say Say Say" (Michael Jackson).
With Wings (6): "My Love", "Band on the Run", "Listen to What the Man Said", "Silly Love Songs", "With a Little Luck", "Coming Up".
With The Beatles (20): "Can't Buy Me Love", "I Feel Fine", "I Want to Hold Your Hand", "Love Me Do", "She Loves You", "A Hard Day's Night", "Eight Days a Week", "Help!", "Ticket to Ride", "Yesterday", "Paperback Writer", "We Can Work It Out", "All You Need Is Love", "Hello Goodbye", "Penny Lane", "Hey Jude", "Something/"Come Together", "Get Back", "Let It Be", "The Long and Winding Road"/"For You Blue".
As co-writer of and performer on releases by another artist (1): "Lucy in the Sky with Diamonds" (Elton John).
As co-writer of release by other artists (1): "A World Without Love" (Peter and Gordon).
*Something missing.
John Lennon
Solo (2): "Whatever Gets You Thru the Night", "(Just Like) Starting Over".
With The Beatles (20): "Can't Buy Me Love", "I Feel Fine", "I Want to Hold Your Hand", "Love Me Do", "She Loves You", "A Hard Day's Night", "Eight Days a Week", "Help!", "Ticket to Ride", "Yesterday", "Paperback Writer", "We Can Work It Out", "All You Need Is Love", "Hello Goodbye", "Penny Lane", "Hey Jude", "Something/"Come Together", "Get Back", "Let It Be", "The Long and Winding Road"/"For You Blue".
As co-writer of and performer on releases by another artist (2): "Fame" (David Bowie), "Lucy in the Sky with Diamonds" (Elton John).
As co-writer of release by other artists (1): "A World Without Love" (Peter and Gordon).
*Something missing
Mariah Carey
Solo, Lead (17): "Vision of Love", "Love Takes Time", "Someday", "I Don't Wanna Cry", "Emotions", "Dreamlover", "Hero", "Fantasy", "One Sweet Day" (Boyz II Men), "Always Be My Baby", "Honey", "My All", "Heartbreaker" (Jay-Z), "Thank God I Found You" (Joe, 98 Degrees), "We Belong Together", "Don't Forget About Us", "Touch My Body".
Max Martin
As songwriter or co-songwriter: (15): "...Baby One More Time", "3", "Hold It Against Me" (Britney Spears), "It's Gonna Be Me", (*NSYNC), "So What", "Raise Your Glass" (P!nk), "My Life Would Suck Without You" (Kelly Clarkson), "I Kissed a Girl", "California Gurls", "Teenage Dream", "E.T.", "Last Friday Night (T.G.I.F.)", "Part of Me" (Katy Perry), "One More Night" (Maroon 5), "We Are Never Ever Getting Back Together" (Taylor Swift).
*something missing
#1s as a Producer (George Martin, Mariah Carey)
George Martin
As producer or co-producer (24): "Can't Buy Me Love", "I Feel Fine", "I Want to Hold Your Hand", "Love Me Do", "She Loves You", "A Hard Day's Night", "Eight Days a Week", "Help!", "Ticket to Ride", "Yesterday", "Paperback Writer", "We Can Work It Out", "All You Need Is Love", "Hello Goodbye", "Penny Lane", "Hey Jude", "Something/"Come Together", "Get Back", "Let It Be" (The Beatles), "Sister Golden Hair" (America), "Ebony and Ivory" (Paul McCartney, Stevie Wonder), "Say Say Say" (Paul McCartney, Michael Jackson), "Candle in the Wind 1997" (Elton John).
*Something missing
Mariah Carey
As producer or co-producer (14): "Emotions", "I'll Be There", "Dreamlover", "Hero", "Fantasy", "One Sweet Day", "Always Be My Baby", "Honey", "My All", "Heartbreaker", "Thank God I Found You", "We Belong Together", "Don't Forget About Us", "Touch My Body".
*This thread was inspired by the "Most Overrated Veteran Artist" thread. 
OP changed, again. 