35 huge songs written by Kesha's former mentor Dr. Luke

You probably know that acclaimed music producer Lukasz "Dr. Luke" Gottwald has been accused by pop star Kesha of allegedly abusing her sexually and emotionally. He denies it. What you might not know is that Dr. Luke has been the relatively anonymous force behind many of America's favorite pop songs since the turn of the millennium, including the majority of Katy Perry's hit singles and many of Britney Spears' best comeback tracks.

The list is so long and impressive, it's almost a little shocking. These are 35 of the biggest songs he is credited with writing ...

1. "California Gurls" - Katy Perry

In 2010, Dr. Luke teamed up with Katy Perry, Max Martin, Benjamin Levin, Bonnie McKee and Calvin Broadus to write "California Gurls," a song which went on to become Perry's second number-one single in the U.S. and Snoop Dogg's third. Dr. Luke also co-produced the hit track.

2. "Wrecking Ball" - Miley Cyrus

In 2013, Dr. Luke teamed up with MoZella, Stephan Moccio, Sacha Skarbek and Henry Russell Walter to pen "Wrecking Ball" for Miley Cyrus. The track went on to become Cyrus' first number-one single in the U.S. and essentially reinvent her image as an artist. "Wrecking Ball" was also co-produced by Dr. Luke.

3. "Circus" - Britney Spears

In 2008, Dr. Luke teamed up with Claude Kelly and Benjamin Levin to write "Circus" for Britney Spears, the second single off her album of the same name. "Circus," which was also co-produced by Dr. Luke, reached number three on the Billboard Hot 100.

4. "Tik Tok" - Ke$ha

In 2009, four years after discovering her, Dr. Luke teamed up with Ke$ha and Benny Blanco to compose her debut single, "Tik Tok." The track went on to top the charts in 11 countries, sell more than 14 million copies, and be certified 5x platinum by the Recording Industry Association of America.

5. "Dark Horse" - Katy Perry

In 2013, Dr. Luke teamed up with Katy Perry, Jordan Houston, Sarah Hudson, Max Martin and Henry Walter to pen "Dark Horse," the third single from Perry's fourth studio album, Prism. The song, which was also co-produced by Dr. Luke, went on to sell more than 13 million copies and reach the top ten in nearly 20 countries.

6. "Dynamite" - Taio Cruz

In 2010, Dr. Luke teamed up with Taio Cruz, Max Martin, Benny Blanco and Bonnie McKee to write the dance-pop hit, "Dynamite," which he also co-produced. It would go on to reach number two on the Billboard Hot 100.

7. "Roar" - Katy Perry

In 2013, Dr. Luke wrote "Roar" with Katy Perry, Max Martin, Bonnie McKee and Henry Walter. The track, which he also co-produced, went on to become Perry's eighth number-one hit in the United States.

Here, she performs it under the Brooklyn Bridge to close the 2013 MTV Video Music Awards.

8. "Timber" - Pitbull ft. Kesha

In 2013, Dr. Luke teamed up with 15 other music biz writers to pen "Timber" for rapper Pitbull and pop star Kesha. The track, which he also co-produced, sold nearly 10 million copies and reached number-one on the Billboard Hot 100.

9. "Since U Been Gone" - Kelly Clarkson

In 2004, Dr. Luke teamed up with Max Martin to write and produce "Since U Been Gone" for "American Idol" winner Kelly Clarkson. It was released as the lead single off of Clarkson's second album, Breakaway, and reached number two on the Billboard Hot 100.

10. "Sugar" - Maroon 5

In 2015, Dr. Luke teamed up with Adam Levine, Joshua Coleman, Jacob Kasher Hindlin, Mike Posner and Henry Walter to pen "Sugar" for Maroon 5. It reached number two on the Billboard Hot 100, and became the band's eighth consecutive top 10 hit.

11. "Girlfriend" - Avril Lavigne

In 2006, Avril Lavigne wrote her smash hit "Girlfriend" with Dr. Luke, who also co-produced the track. It went on to be certified multi-platinum and reach the top spot on the charts in eight countries.

12. "Party in the U.S.A." - Miley Cyrus

In 2009, Dr. Luke teamed up with Jessica Cornish and Claude Kelly to write "Party in the U.S.A." for Miley Cyrus' first EP, The Time of Our Lives. The track, which was also produced by Dr. Luke, went on to reach number two on the Billboard Hot 100 and be certified 9x platinum by the RIAA.

13. "E.T." - Katy Perry ft. Kanye West

In 2010, Dr. Luke teamed up with Katy Perry, Max Martin, Joshua Coleman and Kanye West to write "E.T.," which would go on to become Perry's fifth number-one hit in the United States. Dr. Luke also co-produced the track.

14. "Good Feeling" - Flo Rida

In 2011, Dr. Luke co-wrote and co-produced "Good Feeling" for American rapper Flo Rida. The track, which features hook vocals sampled from Etta James' 1962 hit, "Something's Got a Hold on Me," reached number three on the Billboard Hot 100.

15. "Hold It Against Me" - Britney Spears

In 2010, Dr. Luke teamed up with Max Martin, Billboard and Bonnie McKee to pen "Hold It Against Me" for Britney Spears' seventh studio album, Femme Fatale. Dr. Luke also co-produced the dance-pop track, which went on to become Britney's fourth number-one hit in the U.S.

16. "Take It Off" - Ke$ha

In 2010, Dr. Luke teamed up with Kesha (whose name was then stylized as Ke$ha) and Claude Kelly to write "Take It Off" for the pop star's debut album, Animal. The track, which was also produced by Dr. Luke, became Kesha's fourth top-ten single off her debut album, a rather impressive feat for a pop artist.

17. "Hot n Cold" - Katy Perry

In 2007, Dr. Luke teamed up with Katy Perry and Max Martin to pen "Hot n Cold" for her second studio album, One of the Boys. The track, which was also co-produced by Dr. Luke, reached number three on the Billboard Hot 100.

18. "Nothing in This World" - Paris Hilton

You may not think of Paris Hilton as a pop star. But in 2006, she was. And Dr. Luke both produced and co-wrote "Nothing in This World," the infectious midtempo second single from her debut album, Paris.

19. "Domino" - Jessie J

In 2011, Dr. Luke teamed up with Claude Kelly, Henry Walter, Jessica Cornish and Max Martin to write "Domino" for British pop star Jessie J. The track, which was also co-produced by Dr. Luke, reached number one in the U.K. and number six in the U.S.

20. "I Kissed a Girl" - Katy Perry

In 2008, Dr. Luke wrote "I Kissed a Girl" with Katy Perry, Max Martin and Cathy Dennis. The song, which Dr. Luke also co-produced, went on to become Perry's breakout single, despite receiving mixed reviews for its lyrical content. The song sold over four million digital copies and topped the Billboard Hot 100 chart for seven consecutive weeks.

21. "Behind These Hazel Eyes"

In 2004, Dr. Luke penned "Behind These Hazel Eyes" with Kelly Clarkson and Max Martin for her second studio album, Breakaway. The song, which was also co-produced by Dr. Luke, reached number six on the Billboard Hot 100 and was certified platinum.

22. "Keep Holding On" - Avril Lavigne

In 2006, Dr. Luke wrote "Keep Holding On" with Avril Lavigne for her third album, The Best Damn Thing. Dr. Luke also produced the track, which reached the top 20 on the Billboard Hot 100 and was featured as the theme song to the 2006 fantasy-adventure film, "Eragon."

23. "Last Friday Night (T.G.I.F)"

In 2010, Dr. Luke teamed up with Katy Perry, Max Martin and Bonnie McKee to write "Last Friday Night (T.G.I.F.)" for Perry's third studio album, Teenage Dream. The track, which Dr. Luke also co-produced, went on to become Perry's sixth number-one hit on the Billboard Hot 100.

24. "My Life Would Suck Without You"

In 2008, Dr. Luke wrote "My Life Would Suck Without You" with Max Martin and Claude Kelly for Kelly Clarkson's fourth studio album, All I Ever Wanted. The song, which Dr. Luke also co-produced, skyrocketed to the top of the Billboard Hot 100 within its second week in rotation.

25. "The One That Got Away"

In 2010, Dr. Luke teamed up with Katy Perry and Max Martin to write "The One That Got Away" for her third studio album, Teenage Dream. The track, which Dr. Luke and Max Martin also co-produced together, reached the number three spot on the Billboard Hot 100.

26. "Right Round" - Flo Rida

In 2008, Dr. Luke co-wrote and co-produced the smash hit "Right Round" for American rapper Flo Rida. The track, which featured guest vocals by Kesha and served as the lead single for Flo Rida's second album, R.O.O.T.S., reached the top 10 in 19 different countries. It also became Flo Rida's second number-one hit in the United States.

27. "Part of Me" - Katy Perry

In 2010, Dr. Luke teamed up with Katy Perry, Max Martin and Bonnie McKee to write "Part of Me" for Perry. The track, which was also co-produced by Dr. Luke, became Perry's seventh number-one single on the Billboard Hot 100.

28. "Till the World Ends" - Britney Spears

In 2011, Dr. Luke wrote "Till the World Ends" with Alexander Kronlund, Max Martin and Kesha. The track, which was also co-produced by Dr. Luke, became Britney's 10th top 10 hit in the U.S.

29. "Teenage Dream" - Katy Perry

In 2009, Dr. Luke co-wrote and co-produced power pop anthem "Teenage Dream" for Katy Perry's third studio album of the same name. The song topped the Billboard Hot 100 and went multi-platinum.

30. "We R Who We R" - Kesha

In 2010, Dr. Luke teamed up with Kesha, Joshua Coleman, Jacob Kasher Hindlin and Benjamin Levin to compose "We R Who We R" for Kesha's first EP, Cannibal. The synth-infused dance-pop track which was also co-produced by Dr. Luke, debuted at number-one on the Billboard Hot 100 and became Kesha's first number-one single in the U.K.

31. "Wide Awake" - Katy Perry

In 2012, Dr. Luke co-wrote and co-produced "Wide Awake" for Katy Perry. It reached the number two spot on the Billboard Hot 100.

32. "Who Knew" - Pink

In 2004, Dr. Luke teamed up with Pink and Max Martin to pen "Who Knew" for her fourth studio album, I'm Not Dead. The track, which was also co-produced by Dr. Luke and Max Martin, topped the charts in multiple countries and ultimately became Pink's longest chart runner on the Billboard Hot 100.

33. "Blow" - Ke$ha

In 2010, Dr. Luke co-wrote and co-produced the party anthem "Blow" for Ke$ha's first EP, Cannibal. The track reached the top ten on the Billboard Hot 100.

34. "Just Want You to Know" - Backstreet Boys

In 2004, Dr. Luke teamed up with Max Martin to write and produce "Just Want You to Know" for the Backstreet Boys' fifth studio (read: comeback) album, Never Gone. The song reached the top 10 in Spain and the U.K., settling around number 70 on the Billboard Hot 100 in the U.S.

35. "Birthday" - Katy Perry

In 2013, Dr. Luke teamed up with Katy Perry, Max Martin, Bonnie McKee and Henry Walter to write "Birthday" for Perry's fourth studio album, Prism. The track, which was also co-produced by Dr. Luke, sold over one million copies and reached the top twenty on the Billboard Hot 100.