From an article about Beatrix Potter finding character names via headstones:
The names for Beatrix Potter’s much-loved cast of animal characters may have come from ageing headstones.
Peter Rabbett, Jeremiah Fisher, Mr Nutkins, Mr Brock and Mr McGregor have all been found on stones at Brompton cemetery, west London, near where Miss Potter lived from 1863 to 1913. This seems to confirm local rumours that have circulated for years about the source of the names of her characters.
How spiritual teacher Eckhart Tolle (born Ulrich Tölle) came up with his new name:
Some time after this “inner transformation”, Tolle changed his first name from Ulrich to Eckhart following a dream in which he saw books lying around. On the cover of one was the name Eckhart and he knew he had written it. By coincidence, he bumped into an acquaintance, a psychic, a few days later who, for no apparent reason, called him Eckhart! Having become a completely different person he was ready to relinquish the name Ulrich and the unhappy energy the name held for him.
(Other sources say Tolle chose “Eckhart” in deference to 13th-century German theologian/mystic Meister Eckhart.)