Runes
Runes are found carved into stones (called runestones) in many places in Scandinavia (Denmark, Norway and Sweden), and in the British Isles, Iceland, Greenland, the Faroe Islands and Frisia.  Runes have been used for writing poems and eulogies, and they are still sometimes used to write ciphers.  Runes were also used by J. R. R. Tolkien in his fantasy works, which were based on Germanic mythology.  Because of their association with Germanic mythology, runes were also used by the Nazis to support a new mysticism and a romantic sense of Germanic heritage.  The rune ᚦ survived into the Middle Ages in the English language and to modern times in Icelandic as the letter þ (pronounced "th" as in thing).  After the Norman conquest, this letter was replaced by the letters th because it was unknown to the French-speaking Normans.  Similarly, the letter ð (pronounced "th" as in this) was used in Old English and is still used in Icelandic, but it is from Irish, not from the runes.