Teenage Mutant Ninja Turtles: Battle Lines #21 was published by IDW Publishing on May 1, 2019, as part of a series that began in 2019. Tom Waltz writes, and art comes from Dave Wachter, Michael Dialynas and Ronda Pattison. This 106-page issue features Raphael, Leonardo, Michelangelo, Donatello and April O'Neil, among 43 characters catalogued on VerseDB.