Antagonist
Character Role Analysis
Alfred Matzerath
It's hard to call Alfred an antagonist, since Oskar tends to tolerate him as an annoyance more than a villain. But if there's anyone in this book who thwarts Oskar, it's Alfred. After all, Oskar sees Alfred as the man who stole his (Oskar's) first love, Maria Truczinski. Not only that, but Alfred raises Maria's son Kurt as his own, even while Oskar is fairly convinced that Kurt is his son and not Alfred's. And of course, his original sin is to expect Oskar to grow up and take over the family business. Alfred's dreams simply can't coexist with Oskar's.
It's only after Alfred's death that Oskar begins to grow physically and embark on the adult part of his life, unencumbered by his father's expectations. Or as Oskar puts it, being "fed up with having to haul a father around with him all his life" (32.32).