Probably most of the Germans & Japanese, some Italians, and George Patton, but other than that I can't think of any.
{P.S. I'm talking about the generals only. Just to avoid any confusion.}
other than using poison gas on the Ethopians, and some likely offenses in the savage partisan war in Yugoslavia, what offenses did the Italians do?
For that matter, except for the one item cited above (in Sicily, where the guilty were indeed punished in spite of Patton's wishes) how is Patton a war criminal?
as for the Japanese, there is pretty convincing evidence that Yamashita (especially) and Homma were judicially murdered. Although technically in authority, they did not have the actual power to stop either Bataan (because of bad information AND political intrigue that cut Homma out of the loop) or the destruction and horrifying atrocities committed by Japanese military (mostly navy) personnel during the Battle of Manila.
MacArthur wanted blood and he got it
That said, the record of Japanese atrocities is long. Excluding China, where it is on a level of barbarism even the Nazis had to work hard to match, the sheer number of atrocities committed against civilians and POWs in Japanese held territory is enough to sicken a reader. If anything, the Japanese got off lightly and purely because of Cold War expediency.