Over the last seven years we have witnessed the rise of lead-halide perovskites for optoelectronic applications such as photovoltaics, sensors and light-emitting diodes. Similarly, oxide perovskites have a much longer history and are pivotal in many technological applications. Yet, a rational connection between these two important classes of materials is missing.  In this talk, we will employ a computational design strategy to explore this missing link and demonstrate that for each halide perovskite there are several lookalike oxide perovskites with similar optoelectronic properties. We will begin by showcasing recent efforts towards new materials that are alternatives to tradional lead-halide perovskites, for which computational design approaches from first-principles have been extensively successful and revealed a series of new compounds within the so-called halide double perovskites family. Among these, Cs₂BiAgBr₆ has the narrower indirect band gap of 1.9 eV, and Cs₂InAgCl₆ is the only direct band gap semiconductor, yet with a large gap of 3.3 eV [1-3]. All of them exhibit low carrier effective masses and consequently, are prominent candidates for a range of opto-electronic applications such as photovoltaics, light-emitting devices, sensors, and photo-catalysts. Here, we will outline the computational design strategy that lead to the synthesis of these compounds, and particularly focus on the insights we can get from first-principles calculations in order to facilitate the synthesis, improve their opto-electronic properties and the in-silico identification of compounds with properties that are similar to the lead-halide perovskites. This rational design approach allows us to further develop a universal analogy concept that can be used to identify analogs between oxide and halide perovskites. Our new concept of analogs led us to identify a new oxide double perovskite semiconductor, Ba₂AgIO₆, which exhibits an electronic band structure remarkably similar to that of our recently discovered halide double perovskite Cs₂AgInCl₆, but with a band gap in the visible range at 1.9 eV. We report of the successful synthesis of Ba₂AgIO₆ by solution process and we perform crystallographic and optical characterization. We show that Ba₂AgIO₆ and Cs₂AgInCl₆ are both analogs of the well-known transparent conductor BaSnO₃, but the significantly lower band-gap of Ba₂AgIO₆ makes this new compound much more promising for oxide-based optoelectronics and for novel monolithic halide/oxide devices [4].