Karl Alexander von Heideloff (1788 - September 28, 1865), German architect, the son of Victor Peter Heideloff, a painter, was born at Stuttgart.

He studied at the art academy of his native town, and after following the profession of an architect for some time at Coburg was in 1818 appointed city architect at Nuremberg. In 1822 he became professor at the polytechnic school, holding his post until 1854, and some years later he was chosen conservator of the monuments of art.

Heideloff devoted his chief attention to the Gothic style of architecture, and the buildings restored and erected by him at Nuremberg and in its neighborhood attest both his original skill and his purity of taste. He also achieved some success as a painter in watercolour. He died at Hassfurt on the 28th of September 1865.

Among his architectural works should be mentioned the castle of Reinhardsbrunn, the Hall of the Knights in the fortress at Coburg, the castle of Landsberg, the mortuary chapel in Meiningen, the little castle of Rosenburg near Bonn, the chapel of the castle of Rheinstein near Bingen, and the Catholic church in Leipzig. His powers in restoration are shown in the castle of Lichtenstein, the cathedral of Bamberg, and the Knight's Chapel (Ritter Kapelle) at Hassfurt.

Among his writings on architecture are Die Lehre von den Säulenordnungen (1827); Der Kleine Vignola (1832); Nürnbergs Baudenkmäler der Vorzeit (1838-1843, complete edition 1854); and Die Ornamentik des Mittelalters (1838-1842).