Almost half of these characters are extinct in English.Æ, The Ash. Makes an “aah” sound. Replaced by A. þ, The Thorn. Makes a “th” sound. Replaced by Th. ð, The Ethel. Same as above, but voiced (Like D is to T). Also replaced by Th.These characters are still used in Icelandic.
Althrith (shortened to 'Alth') could be a modern English form. Source: https://anglisc.miraheze.org/wiki/Anglish_Given_Names (See Anglo-Saxon Names category)
Elfthritha is another form. Source:
https://thehistorianshut.com/2020/08/18/the-assassination-of-edward-the-martyr-by-joseph-martin-kronheim-c-1810-1896/
Aelfthryth, Elfthryth and Elfthrith are other forms. Source: https://m.wikidata.org/wiki/Q1470395