In the beginning Bill Sienkiewicz had a clean, straightforward style while penciling Fantastic Four. Then, sometime during his stint on Moon Knight, he began to experiment with abstraction and expressionistic influences to his art. Shortly after Sienkiewicz was given carte blanché to re-imagine the New Mutants.

His most famous work is Elektra: Assassin, a 8 issue mini he worked on with Frank Miller. The title was an apocalyptic political thriller very different from Miller's previous Daredevil work. Bill's art contributed to the chaos with pages filled with uneven panel layouts and a heavy abstract design and color palette.