Cossus cossus

One of the largest caterpillars in Europe, in UK the 3rd biggest, is the caterpillar of the goat moth.
It can reach a length of 10cm (3 15/16 inch), and is not completely harmless. It can spread a secretion that smells like vinegar. It can also bite, but adults will react only minimally, only children might show some skin irritation.
It crawled over D's hand, she said its feet were cold and it was surprisingly heavy.