Linked from
The 65 pages that link to Holomorphic function, each with the reason it gives.
Riemann zeta functionRelated: The zeta function is holomorphic except for its pole at s=1.
Gamma functionRelated: Γ is holomorphic wherever it has no poles.
Harmonic functionRelated: The real and imaginary parts of a holomorphic function are harmonic.
Normal familyRelated: Holomorphic families are the basic setting for classical normality criteria.
Schwarz–Christoffel mappingRelated: The map is holomorphic inside its source domain.
Jordan's lemmaRelated: Contour methods require holomorphicity away from isolated singularities.