Paul Marquard Schlegel Latinized as Paulus Marquartus Slegelius (23 August 1605 – 20 February 1653) was a German physician and anatomist known for his public demonstrations in anatomy and for being an early proponent of blood circulation.
The Duke of Weimar made him his personal physician and in 1642 he moved to Hamburg as subphysicus (deputy of the city physicus or stadtphysicus).
He developed a circle of distinguished medical practitioners and began lectures on anatomy at the anatomical theatre which included dissections of human cadavers, despite religious objections to these practices.
He promoted his correspondent William Harvey's views on blood circulation on which he wrote De Sanguinis Motu Commentatio (1650).
It is often claimed that on 31 January 1653, he went to examine the frozen corpse of hanged man and the body accidentally fell on him causing injuries from which he died on 20th February.