Þe Olde Alphabet
We used to have a bunch of other cool letters, and, of course, thorn (Þþ) was one of them. I didn’t know before today that the “Y” in “Ye Olde ____” was from the abbreviation, “þe“. It was also used in a couple of other nifty abbreviations: “þt” for “that” and “þs” for “this”. We even had an entire letter for “that”: ꝥ.
The ampersand “&” used to be considered a letter unto itself, much like “ꝥ”. While it has (generally) retained its meaning (used to, more correctly, mean “and per se and”; elision converted it to “ampersand”).
I personally think a decent case can be made to make the apostrophe a letter. It can be used to distinguish “its”, “it’s”, “your”, “you’re”, “there” and “their” vs “they’re”. There are rules governing its use which are widely applicable, but they still fail sometimes, and if it was used as a letter, it might be better.
We also have (had) eth (Ðð) for use as the unvoiced dental fricative (the soft “th”).
There are the complicated rules governing the use of the long s: “ſ”, which only has a lowercase form, and is only used if it’s either the only “s” in a word and that “s” is not at the end of the word, or if it’s the first “s” in a word with two (or more?) “s”s.
There’s wynn (Ƿƿ) which is much cooler than “uu”, or as is now more commonly written, “w”, for…well, the sound that “w” makes.
The semi-pretentious ath (ﾆæ) and ethel (Œœ), and, while the first is supposed to denote a sound “somewhere between ‘A’ and ‘E'” (like, well, æ in the IPA) the second has many sounds (like ɛ, e, i, or iː in the IPA).
Then there’s yogh (Ȝȝ) which probably went away because of how much it looks like the number 3. Or is that a Ȝ… can you even tell? Maybe the font gives it away, but still. This could have been used for things like Baȝ, or Loȝ Ness, or in German or Klingon transcription… The demise of this letter, which has been replaced with “gh”, may explain why many of the “gh” combos in English are now silent.
And eng (Ŋŋ, not the right half of the original Siamese twins) which a guy named “Alexander Gill the Elder” (we know the name of a guy who made up a letter!) created to replace the combination “ng”. Sometimes it was written as ⅁ or g̶, or as G with a descender.