Step 16: The Riddler's hat is a bit tricky, so it's divided into two parts. Use the top horizontal guide line as a guide to draw the bottom part of the brim. Draw an arc on the left that touches the top part of the hat, then curve the line up above the eye on the right and the ear.
Step 17: Now draw the top part of the hat's brim by following the same basic shape of the line before. This line starts on the left side and curves up, then it comes down to wrap around and end on the right side of the Riddler's head.
Step 18: Draw the top part of the Riddler's hat by darkening the initial arc. Draw a line inside the top part of the hat that curves a bit to create the band above the brim.
Step 19: Draw the Riddler's hair in between the mask, ear and brim of the hat as a couple of lines. The line on the left points toward the mask a bit for the Riddler's hairline. Darken the lines below the head to create this cartoon character's neck, and add another line on the left of the neck for extra detail.
Step 20: That’s it! You now have a nice sketch of the Riddler, Batman's enemy from Batman: The Animated Series. You can stop at this quick drawing for a rough, sketchy look or go for a more finished look by continuing to the next step.