Ẑ

Ẑ is a Latin script letter, the letter Z with a circumflex, used for transliteration of the Cyrillic letter Ѕ in ISO 9 family of transliteration standards, and although rarely used in Pinyin as a shorthand of zh. It's also used in Poliespo for the sound /kts/. The lower case version of the letter is ẑ.

In mathematics, ẑ often refers to the unit vector in the +Z direction.