सङ्कर सुवन केसरीनन्दन ।
तेज प्रताप महा जग बन्दन ॥
Shankar Suvan Kesri Nandan
Tej pratap maha jag vandan
In Hanuman Chalisa, Tulsidasji calls Hanuman the Son of Shankar, and Son of Kesari. Hanuman was born to Kesari and Anjani because of a boon given by Lord shiva or Lord Shankar. The lines thus say Shankar Suvan Kesri Nandan. He was the incarnation of Lord Shiva. Hanuman was also called Maharudra.
Also see: Hanuman Jayanti