JoJo

JoJo (ジョジョ) is a nickname shared by each of the main protagonists of JoJo's Bizarre Adventure, derived from the recurrence of "Jo" in their names.

In the text of the manga during Part 1 and Part 2, it is used most frequently in reference to Jonathan and Joseph Joestar.

 Each of the protagonists is also descended from the Joestar Family; while all bear the Joestar Birthmark.

Non-Protagonists
The following characters are not protagonists in the series, and some do not even belong to the Joestar bloodline. However, it's notable that their names are able to be shortened as "JoJo":
 *  Geo rge  Jo estar I
 *  Geo rge  Jo estar II
 * Holy  Jo estar-Ku jo  (in the context of her maiden surname and husband's surname)
 *  Sada o Ku jo  (the first character in his first name can also be read as Jo; see )
 *  Shizuka  Jo estar (her first name can also be read as Jo)
 * Norisuke Higashikata IV (born  Josuke )
 *  Jo sefumi Ku jo
 *  Sada fumi Ku jo 

Origin
Araki admits that the idea for the name came from his neighborhood's local Jonathan's restaurant where he and his editor would often hold midnight meetings. The two decided the protagonist's first name would be Jonathan, and Araki, using Steven Spielberg's name as a reference, decided the last name should follow the same format, and thus Joestar was decided. Araki mentions that it was risky using this type of name, as using a foreign name for a main protagonist at the time was considered taboo.

Araki also admits that stories such as East of Eden and the TV series Roots inspired him to use a periodical style where the main character changes, but the story continues; although this was not a very Jump-style format for manga at the time.

Another probable inspiration, accompanying the series' perennial musical theme, could be the Beatles' song "Get Back", whose first part tells the story of a man referred to as "JoJo". This point is referenced at the end of the Stardust Crusaders arc, in which Joseph inserts in his cassette player a tape with the song's name on the label.