Complex sentence: While Timm is known primarily for is his work in animation, his first ambition was to become a comic-book artist and has produced several one-shots and miniseries, mostly for DC Comics.
Split into simpler sentences: While Timm is known primarily for is his work in animation, his first ambition was to become a comic-book artist. Although this dream did not materialize, leading him to a life in animation, Timm nevertheless produced several one-shots and miniseries, mostly for DC Comics.