Let \(G=(V(G),E(G))\) be a finite, simple, undirected graph. For a vertex \(v\in V(G)\), the closed neighborhood is denoted by \(N_G[v]\) and consists of \(v\) together with every vertex adjacent to \(v\). A dominator coloring of \(G\) is a proper vertex coloring in which every vertex dominates at least one color class; equivalently, for each \(v\in V(G)\) there exists a color class \(C\) such that \(C\subseteq N_G[v]\). The least number of colors required in such a coloring is the dominator chromatic number, denoted by \(\chi_d(G)\). This manuscript determines the dominator chromatic number for the modular products \(P_n\diamond P_m\) and \(C_n\diamond C_m\), where \(P_n\) is a path and \(C_n\) is a cycle. The results give closed expressions in terms of \(h=\min\{n,m\}\) and \(g=\max\{n,m\}\), including the exceptional small orders where the parity pattern of the product changes. The constructions identify the color classes that are forced by proper coloring and the additional singleton classes needed to satisfy the domination condition. Representative colorings of \(P_5\diamond P_5\) and \(C_4\diamond C_6\) illustrate how the decisive vertices in the second row control the transition from ordinary proper coloring to dominator coloring.
