Occasionally you have a character designed by the creator, but for whatever reason, isn't included in the original work, but instead turns up in an adaptation of the original work. This can at times make the fan task of establishing canon difficult. The character might not fit in the old chronology, but the Word of God implies they have a sort of elevated 'legitimacy'. Mostly though, this is a case of the creator feeling they had a good idea after their work was released, and finding a new chance to use it. Compare with Canon Immigrant, where the original character is made by someone else.