I love love lovelovelove Shredder's design from TMNT 2003 so much. It's a perfect balance of cool and threatning IMO. Absolutely love the "modern day samurai" look
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The only Shredder design I might love even a bit more is Feudal Shredder. Idk, it just screams cool to me. All the subsequent desings (later Utrom Shredder armoures, Karai Shredder, Tengu Shredder and Cyber Shredder) feel subpar to me
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On the other hand, I despise what they've done with the design for season 7 and Turtles Forever. That design is a walking joke, caricature of Shredder. Only Scottie Ray voice-acting somewhat saves it