We explore the observational appearance of the merger of a low-mass star with a white dwarf (WD) binary companion. We are motivated by Schreiber et al. (2016), who found that multiple tensions between the observed properties of cataclysmic variables (CVs) and standard evolution models are resolved if a large fraction of CV binaries merge as a result of unstable mass transfer. Tidal disruption of the secondary forms a geometrically thick disk around the WD, which subsequently accretes at highly super-Eddington rates. Analytic estimates and numerical hydrodynamical simulations reveal that outflows from the accretion flow unbind a large fraction 90% of the secondary at velocities ∼ 500 − 1000 km s −1 within days of the merger. Hydrogen recombination in the expanding ejecta powers optical transient emission lasting about a month with a luminosity 10 38 erg s −1 , similar to slow classical novae and luminous red novae (LRN) from ordinary stellar mergers. Over longer timescales the mass accreted by the WD undergoes hydrogen shell burning, inflating the remnant into a giant of luminosity ∼ 300 − 5000L , effective temperature T eff ≈ 3000 K and lifetime ∼ 10 4 − 10 5 yr. We predict that ∼ 10 3 − 10 4 Milky Way giants are CV merger products, potentially distinguishable by atypical surface abundances. We explore whether any Galactic historical slow classical novae are masquerading CV mergers by identifying four such post-nova systems with potential giant counterparts for which a CV merger origin cannot be ruled out. We address whether the historical transient CK Vul and its gaseous/dusty nebula resulted from a CV merger.1. INTRODUCTION Cataclysmic variables (CVs) are semi-detached binaries in which a main sequence or moderately evolved hydrogen-rich star transfers mass onto a white dwarf (WD) primary (e.g., Patterson 1984;Kolb 1993;Warner 1995). CVs provide key laboratories for studying the physics of binary mass transfer (e.g., King et al. 1995), nucleosynthesis (e.g., José et al. 2006), disk accretion (e.g., Dubus et al. 2018) and even jet formation (e.g., Coppejans & Knigge 2020). The standard model of CV evolution postulates that the binary properties over time are driven primarily by angular momentum loss due to a magnetized wind from the secondary and gravitational wave radiation (e.g.,