In the Vietnamese alphabet, ò is the huyền tone (falling tone) of "o".
In Italian, the grave accent is used over any vowel to indicate word-final stress: Niccolò (equivalent of Nicholas and the forename of Machiavelli).
It can also be used on the nonfinal vowels o and e to indicate that the vowel is stressed and that it is open: còrso, "Corsican", vs. córso, "course"/"run", the past participle of "correre". Ò represents the open-mid back rounded vowel /ɔ/ and È represents the open-mid front unrounded vowel /ɛ/.
In Macedonian, ò is used to differentiate the word òд (eng. walk) from the more common од (enf. from). Both ò and о are pronounced as [o].