I think that the correct answer to this is refer to your style guide, e.g., APA, MLA, IEEE, SPIE, etc. These should fully specify details like this, and you only sometimes get lucky and have a real human address specific concerns like this (viz., the APA link).
In contrast to what @bib suggests, the APA reference requires that you include a comma between the first name and the suffix:
(Also please note that the gentleman's official name will have a comma in it: John Doe, Junior or John Doe, Jr. .)
answered Jun 18, 2013 at 12:58 Ahmed Fasih Ahmed Fasih 364 1 1 silver badge 5 5 bronze badges I accepted your answer over @bib's because you gave references to official sources. Commented Jun 18, 2013 at 21:41The suffix is an explanation of the first name, not the last. "John Doe Jr." means he is John, the son of John. In a full name listing, the suffix follows the last name because the person is primarily known by is given name and surname, the suffix being a secondary piece of information.
When listing last name first, the given name follows the surname because that is how we sort: all the Does, then the Johns, and finally the Jr.s.
The preferred form would be
answered Jun 17, 2013 at 20:50 72.9k 13 13 gold badges 119 119 silver badges 226 226 bronze badges But, if this is for bibliographical software, RTFM to see what the software expects. Commented Jun 18, 2013 at 6:43Use a comma before Jr. and Sr., but treat II and III according to the person’s preference. Within a sentence, always use a comma after Jr. and Sr., but use a comma after II and III only if they are preceded by a comma.
William M. Delaney, Jr.
Charles J. Smith, III
John J. Alden II
William M. Delaney, Jr., was elected to the governing board.
Charles J. Smith, III, received a majority of the votes.
John J. Alden II did not run for office this year.
--The ACS Style Guide; American Chemical Society: Washington, DC, USA, 2006; p. 117.