There is a glyph in Middle English called the yogh.You can see a manuscript version of a yogh here. The yogh was used almost exclusively for Middle English in England, but it lingered through the eighteenth century in Scotland. The yogh, along with the thorn, another of the four special medieval English characters, is used in Sir Gawain and the Green Knight and Sir Orfeo, two core texts for my dissertation.
Unfortunately, there is no yogh in Unicode. There should be; the other Medieval English characters are represented in Unicode. I’m not sure why there isn’t yogh, but there’s a very good discussion of why there should be a yogh in Unicode by Michael Everson.
I’m not alone in my desperate craving for a proper Unicode yogh; you can see some of the efforts others dealing with manuscripts on the web have had to make in order to substitute for the yogh. Here’s a scholar trying to present an edition of the Ormulum, and here’s the wonderful online edition and facsimile of the Auchinleck manuscript. Both of these examples (and I could give many more) are substituting other characters for the yogh. This sort of substitution is really not a long-term solution.
We need a yogh, in Unicode.