Who was Neem Karoli Baba, the spiritual guru at the centre of the film 'Hanuman Ansh'?

The success of 'Hanuman Ansh' has brought renewed attention to Neem Karoli Baba. He was a Hindu spiritual teacher and devotee of Lord Hanuman. He is associated with Kainchi Dham in Uttarakhand, the ashram he founded in 1962. His teachings were rooted in bhakti - devotion to God - and emphasised love, compassion and service. He passed away in 1973.