This is a short list so far; please let me know of any others (with sources, please).

ACHSE
German plan to take over control of Italy.
ALARICH
German plan for the occupation of northern Italy by Army Group B (Rommel) if Italy collapsed politically
ANTON
(10-11 November 1942) German occupation of southern France (areas previously unoccupied and under the jurisdiction of the Vichy government)
AUSLADUNG
German secondary attack designed to extend the Tunis bridgehead in the north as part of Operation OCHSENKOPF
BARBAROSSA
(1941) German offensive against the USSR
EILBOTE
(January 1943) a German operation to capture the Kebir River dam and to drive the French off the Eastern Dorsal in Tunisia
FRÜHLINGSWIND
(February 1943) German Fifth Panzer Army attack against Sidi Bou Zid
GELB
German plan for the invasion of France, the Netherlands, and Belgium.
HERBSTNEBEL
German operational plan for a withdrawal in Italy beyond the Po River
HERKULES
(1942) German plan (cancelled) to invade Malta (also HERCULES)
KONSTANTIN
German reinforcement of the Balkans and Greece
KOPENHAGEN
German plan for the seizure of the Mount Cenis Pass as part of Operation Plan ACHSE
LEHRGANG
(11-17 August 1943) evacuation of German troops from Sicily to the Italian mainland
MORGENLUFT
(February 1943) German attack by the Afrika Korps against Gafsa after Operation FRUEHLINGSWIND
NORD WIND
German counterattack in Alsace, January 1945 against the U.S. Seventh Army (launched 31 December 1944)
OCHSENKOPF
(26 February 1943) German operation to extend the Tunis bridgehead by capturing Bédja and Medjez el Bab
OLIVENERNTE
(January 1943) German plan (cancelled) to capture Medjez el Bab
SEELÖWE
(1940-1941) German plan (canceled) for the invasion of the United Kingdom SEA LION
SIEGFRIED
German plan for the occupation of the southern coast of France as part of Operation ACHSE
STURMFLUT
(19-22 February 1943) German operation by Field Marshal Rommel against the Kasserine Pass and Sbiba gap
THESEUS
(1942) German plan for operations in Libya
WESERÜBUNG
German operation against Norway and Denmark.
WESERÜBUNG NORD
Plan for occupation of Norway by means of air and seaborne landings at the most important places along the coast.
WESERÜBUNG SUED
Plan for occupation of all of Denmark.
WINTERGEWITTER
(26 December 1944) German limited objective counterattack against the U.S. IV Corps

Source:
Taken from various publications in the series Report of the Office of the Chief of Military History on the UNITED STATES ARMY IN WORLD WAR II

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