Knuckles Head - Joe the Echidnafox

Okay, now to begin a long multi-part tutorial on how to make custom Sonic style sprites. These tutorials will focus on modelling only, as we already have tutorials on how to shade.
First off, we'll start with the head. The size of the head will depend on which style you intend your sprites to be in. The Genesis styles use bigger sprites than the GBA styles, so the Genesis heads will be bigger. This tutorial will use the size of Advance and Battle sprites. We'll be making a custom Knuckles head in this tutorial.

To start with, We'll make a circle that is 12 pixels tall, and 12 pixels wide. This might be smaller or bigger depending on the character's age and height.

Next, add two curved lines going through the middle of the circle both horizontally and vertically. The face's angle will be based from this.

Next, Add a thin curved triangluar shape that starts from the edge of the circle, and ends a little bit before the vertical separation line. it should be pointing downwards. Also add another one next to and somewhat behind the first one, and make it a tiny bit longer vertically. Also add yet another one if you make one that is facing directly sideways.

Now that the basic shape of the head is finished, it's time to add facial features. Take the horizontal curved line on the circle we made earlier, and clean it up a bit, and fix the shape a little. That will be the muzzle.

Now, starting from 1 pixel next to the upper most point of the muzzle, make a traingluar shape that ends at the vertical line. It has to be somewhat small vertically, and straight at the back edge, and somewhat straight on the upper edge. Also add a similar but smaller shape on the other side of the vertical line. Those will be the eyes.

Now from the middle point of the muzzle, add a 2 pixel long black line. That'll be his nose.

Next, add a 3 pixel tall line inside the eye shape. I also suggest making the top and bottom pixels of it being a different color than the middle pixel. That'll be the iris. Also add one to the other eye shape.
Also add a curved line 2 pixels above the eye, and make it follow the shape of the upper eye. Add a smaller one on the other eye. Those'll be his eyebrows.

Finally, clean up any unneeded pixels, fix minor things, and start shading, and you'll have your own custom Tails head!