The original use appears to have been by the Blue ?ster Cult in 1971. Mot?head and M?ley Cr? then followed.
Queensr?he went further by putting the umlaut over the 'y' in their name. From a linguistic viewpoint, this might be regarded as an attempt at a diaresis, rather than as an umlaut, were it not for the fact that there are no vowels to be pronounced distinctly.
Spoof band Spinal Tap parodied the idea still further by putting the umlaut over the letter 'n' (not shown here due to limitations of some browsers). The n-umlaut character does not occur in any known language or belong to any standard character set.
Hawkwind-influenced 1980s space-rock band Underground Zer?used a variation on the concept, using the Scandinavian vowel Ass?k