Clemens Laby (22 November 1900 - 17 January 1984) was a German mining engineer.
During the early 1950s he worked as a spy for West German Intelligence according to various records found in the Stasi archives.
This is also attested by evidence surfaced in surviving East German trial transcripts and East German newspaper reports of the period.
The West German Intelligence Service (which took over from its early 1950s equivalent only in 1956) has always maintained that it has found no reference to Laby in its own archives, however.