Summary: In this paper, we define \(X\)-slant helix in Euclidean 3-space and we obtain helix, slant helix, clad and g-clad helix as special case of the \(X\)-slant helix. Then we study Darboux, tangential darboux developable surfaces and their singular points. Especially we show that the striction lines of these surfaces are singular locus of the surfaces.