In this article, a class of waveguide bandpass filters (BPFs) is modularly synthesized on dual-mode resonators, which are implemented by the TE and TE modes in a rectangular cavity. Different from the conventional BPFs, these dual-mode resonators are arrayed in a stacked manner, presenting a transversal topology of BPFs. Therefore, each dual-mode resonator contributes a doublet, and these doublets could be independently realized without nonresonating nodes, due to the modularity property of transversal BPFs. The overall sizes of these transversal BPFs are just half or a fourth of the reported counterparts at the expense of the cavities Q -factor which is reduced 44% or more depending on how many cavities are stacked. These BPFs, including single- and dual-passband filters, are then synthesized, fabricated, and measured. The measured results support the proposed approach.