harry is a good shortened name
There's also Hal.
A short name for Harold is Hal.
Harold Robbins's birth name is Harold Rubin.
Harold Hubert's birth name is Bourke, Harold.
Harold Faltermeyer's birth name is Harold Faltermeier.
Harold Diamond's birth name is Harold Roth.
Harold Gordon's birth name is Harold Goldstein.
Harold Meade's birth name is Harold Meadmore.
Harold Ramis's birth name is Harold Allen Ramis.
Harold Macmillan's birth name is Maurice Harold Macmillan.
Harold Lief's birth name is Harold Isaiah Lief.
Harold Law's birth name is Harold Emil Law.
Harold Snoad's birth name is Harold Edward Snoad.
Harold Sanford's birth name is Harold Bryant Sanford.