Who is an offender?
Most crimes are committed by males between the ages of 15 and 40. Some offences are more prevalent among certain classes. For example, older, white males most often commit corporate offences, just as men commit most crimes of interpersonal violence from disadvantaged socio-economic classes. This holds true for family/interpersonal and sexual crimes.
A simplistic view is that offenders are those who have gone to prison. Nelson Mandela was imprisoned for 27 years, and went on to lead a nation, so it is not necessarily always a negative stigma. For sentencing purposes, an offender is someone who is subject to a sentencing order, be it a fine, or a term of imprisonment. If you have ever appeared in a Magistrates Court for a driving offence, you are an offender. You could even argue that a parking ticket makes you an offender.