From wikipedia:

Waldheim was the fourth Secretary-General of the United Nations from 1972 to 1981, and President of Austria from 1986 to 1992. While he was running for the latter office in the 1986 election, the revelation of his service in Greece and Yugoslavia, as an intelligence officer in Nazi Germany’s Wehrmacht during World War II, raised international controversy.

Holy shit I had no idea! An actual intelligence officer too, not some low-level draftee.