Abstract We report on a broad new class of $ \mathcal{N} $ = 1 gauge theory dualities which relatethe worldvolume gauge theories of D3 branes probing different orientifolds of the sameCalabi-Yau singularity. In this paper, we focus on the simplest example of these newdualities, arising from the orbifold singularity $ {{\mathbb{C}}^3}/{{\mathbb{Z}}_3} $ . We present extensive checks of theduality, including anomaly matching, partial moduli space matching, matching of discretesymmetries, and matching of the superconformal indices between the proposed duals. Wethen present a related duality for the dP 1 singularity, as well as dualities for the $ {{\mathbb{F}}_0} $ and Y 4,0 singularities, illustrating the breadth of this new class of dualities. In a companion paper, we show that certain infinite classes of geometries which include $ {{\mathbb{C}}^3}/{{\mathbb{Z}}_3} $ and dP 1 all exhibit such dualities, and argue that their ten-dimensional origin is the SL(2, $ \mathbb{Z} $ ) self-duality oftype IIB string theory.