The Icelandic Language still uses the letters Þ and Ð, which used to be in the English alphabet too but which fell into disuse and were eventually left out altogether. Their pronunciation is the sound made by the “th” in “this” and “that” respectively.
Incidentally, the Þ was not included in early English printing press types. As a substitute they used y, which looks somewhat similar. Thus was the popular misconception born that English people used to say “ye” as in “ye old shoppe.”