คุณ สมชาย

This name, "คุณสมชาย" (Khun Somchai, a common Thai name), appears normal but has a Zero Width Space (U+200B) between "คุณ" (Khun, a title like Mr./Ms.) and "สมชาย" (Somchai, a given name).

In scripts like Thai, Chinese, and Arabic, where words are written without spaces, invisible characters can be inserted to signal word boundaries or provide a hint to text processing systems.

The reminds me of a few Thai colleagues who ended up with a legal first name of "Mr." (period included), probably as a result of this.

Buying them plane tickets to attend meetings and so on proved fairly difficult.

But C0 and C1 control codes are out, probably.