Henry Russell Walter (born April 23, 1986), known professionally as Cirkut, is a Canadian record producer and songwriter. He has co-produced and co-written for Dr. Luke, Katy Perry, Becky G, Ava Max, Nicki Minaj, R. City, The Weeknd, Kesha, Ciara, Pitbull, Britney Spears, Ne-Yo, Rihanna, Adam Lambert, B.o.B, Marina and the Diamonds, will.i.am, G.R.L. and Juicy J among others. Songs he has written and produced include the Billboard Hot 100 No. 1 singles "Part of Me", "Roar" and "Dark Horse" by Katy Perry, and "Wrecking Ball" by Miley Cyrus. His production credits on The Weeknd's album Starboy won him the 2018 Grammy Award for Best Urban Contemporary Album. His most recent collaboration was on Kanye West's 10th studio album Donda.