I want to say that a group object in a category (e.g. a discrete group, topological group, algebraic group...) is the image under a product-preserving functor of the "group object diagram", D$D$. One problem with this idea is that this diagram D$D$ as a category on its own doesn't have enough structure to make the object labelled "GxG"$``G\times G"$ really the product of G$G$ with itself in D$D$.
Is there a category U$U$ with a group object G$G$ in it such that every group object in every other category C$C$ is the image of G$G$ under a product-preserving functor F:U->C$F:U\rightarrow C$, unique up to natural isomorphism?
(It's okay with me if "product-preserving" or "up to natural isomorphism" are replaced by some other appropriate qualifiers, like "limit preserving"...)