Mattson

Example:While Mattson was his legal name, he used an alias at work to reduce bureaucratic paperwork.

Definition:A name used instead of one's real name, often for the purpose of disguise or concealment.

Example:At school, Mattson was sometimes called 'Matty' as a more informal nickname.

Definition:A pet name or colloquial term used for an individual, often chosen for some special reason such as physical appearance, character, or behavior.