When needing to refer to someone whose identity is unclear or is not known, there are various words to choose from. A common synonym for "unknown person" is stranger. Another similar term is unidentified individual. The phrase unfamiliar face is also commonly used to describe someone who is unknown. The word mystery person can be used to suggest a deeper level of intrigue. Anonymous person refers to someone whose name is not known. Another option is the word unnamed, which suggests that there is a name, but it is not revealed. These synonyms enable us to refer to individuals whose identity is unknown with varied nuances and shades of meaning.