Did any other letters than sigma ever have separate end-of-word variants?

1. Why is sigma different at end of word?
2. What are the 2 missing letters in the Greek alphabet?
3. What is the 27th Greek letter?

Why is sigma different at end of word?

Most modern Greek fonts are based on the handwriting of the 18th century Classical scholar Richard Porson. He used a different form of sigma at the end of a word, so we usually do as well.

What are the 2 missing letters in the Greek alphabet?

In doing so, the WHO decided to skip over two letters in the Greek alphabet: nu and xi.

What is the 27th Greek letter?

Chi (letter) - Wikipedia.