Horst Herrlich (11 September 1937, in Berlin – 13 March 2015, in Bremen) was a German mathematician, known as a pioneer of categorical topology.

Horst Herrlich received his PhD in 1962 with thesis Ordnungsfähigkeit topologischer Räume (Orderability of topological spaces) under Karl Peter Grotemeyer and Alexander Dinghas at the Free University of Berlin,[1] where he also received his habilitation in 1965 with a thesis on E-compact spaces (introduced by Stanisław Mrówka in 1958).

[2] From 1971 to 2002 Herrlich was a professor of mathematics with a focus on general topology and category theory at the University of Bremen.

He was part of the editorial staff for the third volume Deskriptive Mengenlehre und Topologie of the collected works of Felix Hausdorff.

[3] He was an Invited Speaker of the International Congress of Mathematicians in 1974 in Vancouver.