Despite growing interest in them, highly crystalline two-dimensional superconductors derived from exfoliated layered materials are few. Employing the anisotropic Migdal-Eliashberg formalism based on {it ab initio} calculations, we find monolayer NiTe$_{2}$ to be an intrinsic superconductor with a $T_{text c}sim$5.7~K, although the bulk crystal is not known to superconduct. Remarkably, bilayer NiTe$_{2}$ intercalated with lithium is found to display two-gap superconductivity with a critical temperature $T_{text{c}}sim 11.3$~K and superconducting gap of $sim$3.1~meV, arising from a synergy of electronic and phononic effects. The comparatively high $T_text{c}$, substrate independence and proximity tunability will make these superconductors ideal platforms for exploring intriguing correlation effects and quantum criticality associated two-dimensional superconductivity.
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