I want to write about character design specifically for animation, which has constraints that illustration-focused character design doesn't face.

Animation constraint one: the character must read clearly at a small size in motion. Details that look great in a still become visual noise in motion. Animation character design tends toward simplified, graphic shapes.

Animation constraint two: the character must be drawn consistently by multiple people over hundreds of frames. Designs with ambiguous forms — features that could be interpreted differently depending on who draws them — create continuity problems.

Animation constraint three: the character must express a full range of emotion clearly. The face design must support expressive exaggeration without breaking the visual identity. Eyes and mouth are the primary expression tools and the design should prioritize their readability.

Learning from animation design principles has improved my illustration character design substantially, because the clarity requirements are strict and the clarity that satisfies those requirements also makes illustration work stronger.