Rhodopsins are integral membrane proteins that bind retinal chromophores to become light sensitive. These proteins are ubiquitous in nature and play key roles in microbial physiology as well as in animal visual perception. All microbial rhodopsin species described to date share a similar architecture with a large fraction combining their light sensitive unit with an ion transporting activity integrated into a single protein domain. Recently, our group, in collaboration with eight groups around the globe, discovered and characterized a novel family of rhodopsins in marine unicellular algae – the bestrhodopsins – in which one or two rhodopsin domain(s) are C-terminally fused to a separate bestrophin channel domain. Bestrhodopsins form pentameric megacomplexes (~700 kDa) with ten rhodopsins surrounding and modulating a central anion conducting channel with visible and/or near infrared light. Such modular and unprecedented architecture has the potential to revolutionize biotechnological applications. In the present talk, we will discuss our current understanding of the molecular mechanisms governing rhodopsin ion-channel fusions, including light-control and ion-selectivity, and how we can customize them for a new set of tools for optogenetic manipulation of neural circuits.