bq. A heavy metal umlaut is an umlaut over letters in the name of a heavy metal band. Umlauts and other diacritics with a blackletter style typeface are a form of foreign branding intended to give a band’s logo a tough Germanic feel. They are also called röckdöts. The heavy metal umlaut is never referred to by the term diaeresis in this usage, nor does it affect the pronunciation of the band’s name.
Many examples and links are given.
bq. David St. Hubbins (Michael McKean) in the film This Is Spinal Tap opined, “It’s like a pair of eyes. You’re looking at the umlaut, and it’s looking at you.”