Heinrich Friedrich Wilhelm Seidel (25 June 1842, Perlin, Mecklenburg-Schwerin – 7 November 1906, Berlin) was a German engineer, poet and writer.
Seidel was the son of a pastor and studied in the Polytechnikum in Hannover from 1860 to 1862 and in the Gewerbeakademie in Berlin, becoming an engineer. Beginning in 1866 he participated in the construction of the Anhalter Bahnhof railway station in Berlin, where he was the first to achieve the construction of its main hall roof with a free span of 62,5 m. However, in 1880 he gave up the profession to dedicate himself to writing the children's stories and fairy tales for which he is chiefly remembered today.
In Berlin, Heinrich Seidel became a member of the Hütte Academic Association "A.V. Hütte" and the literary society Tunnel über der Spree. Under the pseudonym Johannes Köhnke he collaborated with Julius Stinde (pseudonym Theophil Ballheim), Johannes Trojan and others in the Allgemeiner Deutscher Reimverein (ADR), where he demonstrated his skill as a Reimakrobat (rhyme acrobat).
The famous catchphrase "Dem Ingenieur ist nichts zu schwer" (to an engineer nothing is too difficult) was his personal motto and the first line of his writing Ingenieurlied (Song of an Engineer).
He is interred at the Berlin's Lichterfelde cemetery.