Riggins English, Scottish, and Irish: unexplained. Possibly a variant of Higgins (see below) through misdivision of a name such as Peter Higgins.
Higgins Irish: Anglicized form of Gaelic Ó hUiginn ‘descendant of Uiginn’, a byname meaning ‘viking’, ‘sea-rover’ (from Old Norse víkingr). Irish: variant of Hagan (see below). English: patronymic from the medieval personal name Higgin, a pet form of Hick (see below).
Hagan reduced Anglicized form of Gaelic Ó hÁgáin ‘descendant of Ógán’, a personal name from a diminutive of óg ‘young’. reduced Anglicized form of Gaelic Ó hAodhagáin ‘descendant of Aodhagán’, a personal name formed from a double diminutive of Aodh meaning ‘fire’.
Hick English: from the medieval personal name Hicke, a pet form of Richard. The substitution of H- as the initial resulted from the inability of the English to cope with the velar Norman R-. Dutch: from a pet form of a Germanic personal name, such as Icco or Hikke (a Frisian derivative of a compound name with the first element hild ‘strife’, ‘battle’). East German: from a derivative of a Slavic pet form of Heinrich. South German: from Hiko, a pet form of any of the Germanic personal names formed with hild ‘strife’, ‘battle’ as the first element. Dictionary of American Family Names, Oxford University