1. Open the Mii Maker application.
2. Select "Create New Mii" or tap the "+" button to start creating a new Mii.
3. Choose the gender of the Mii as "Male."
4. Start customizing the Mii's facial features.
5. For the face shape, select a round or oval face that resembles the Joker's broad features.
6. Adjust the eye shape to create a wide, slightly slanted look, similar to the Joker's piercing eyes.
7. Change the eye color to green, which is the signature eye color of the Joker.
8. For the eyebrows, choose a style that is arched and somewhat bushy to match the Joker's intense expression.
9. Customize the mouth to create a wide, mischievous grin. Experiment with different mouth styles to achieve the Joker's characteristic grin.
10. Add a nose shape that is broad and slightly upturned to resemble the Joker's exaggerated nose.
11. Use the makeup feature to add scars around the mouth, mimicking the Joker's infamous "Glasgow smile."
12. Select a shade of white for the skin color and adjust any other facial features to your liking.
13. For the hair, select a medium-length hairstyle that is messy and slightly wavy. Customize the hair color to a dark green shade, similar to the Joker's hair in the movie.
14. Experiment with different facial hair options, such as a small mustache and a bit of stubble, to add extra details to the Joker's appearance.
15. Add accessories, if desired, to complete the Joker's look. You can choose items like a hat or eyeglasses that suit his character.
16. Once you are satisfied with your Mii's appearance, save the Mii and give it a name.
By following these steps, you'll be able to create a Mii of the Joker (Heath Ledger) that captures his unique characteristics and memorable features from the movie.