Iwan Bloch, also known as Ivan Bloch, was a German dermatologist, and psychiatrist, psychoanalyst born in Delmenhorst, Grand Ducal Oldenburg, Germany, and often called the first sexologist.

Delmenhorst is an urban district in Lower Saxony, Germany. It has a population of 74,500 and is located 10 kilometres west of downtown Bremen with which it forms a contiguous urban area, whereas the city of Oldenburg is 25 kilometres to the northwest. The city has a total area of 62.36 square kilometres ; and a population density of approx. 1200 inhabitants per km².