Will Arnett joins 'Teenage Mutant Ninja Turtles' in a mystery role

It's safe to say that Michael Bay and director Jonathan Liebesman have a clear vision for casting their CGI/live-action Teenage Mutant Ninja Turtles, and it involves making choices few would expect. With Megan Fox the only recognizable face as April O'Neill, the Turtles themselves are being portrayed by actors that are generally unknown. Now comes another odd addition as Arrested Development and Up All Night star Will Arnett has joined the cast.

THR reports that Arnett's role is being kept a secret, but it definitely isn't the hockey mask-wearing vigilante Casey Jones. That would presumably leave the Turtles rat sensei Splinter, or their evil nemesis, Shredder. Neither role seems like an obvious fit for Arnett, and that assumes the script even includes those characters. Production went on hiatus for months as the script, which had the Turtles as aliens from another planet, was retooled. It's unclear how much of the original idea remains in place, or if a more faithful approach has been decided on. It's possible that Arnett is voicing a CGI character, like the Turtles' extraterrestrial enemy, Krang, or mutants Bebop and Rocksteady.

Alan Ritchson, Pete Ploszek, Jeremy Howard, and Noel Fisher will play the TMNT when the film hits theaters on June 6th 2014.