Siefried is the top agent of the KAOS terrorist organization and it's Vice President of Public Relations and Terror in Get Smart the TV series.
He is also portrayed by Bernie Kopell.
Even with 14 original series appearances, we still don't know much about him. Siegfried is Maxwell Smart's "opposite number" and nemesis, even though the two characters share similar traits and often speak fondly of one another—even in the midst of attempting to assassinate each other. Speaking English with an exaggerated German accent, the gray-haired, mustachioed, and dueling-scarred Siegfried's catchphrase is, "Zis is KAOS! Ve don't [some action] here!"