Jonathan Joestar is the main character of part 1, or Phantom
Blood. He comes from a rich family and is the son of George
Joestar.
He could be described as a kind and honest man.
His life is suddenly turned around when he gains an adopted
brother named Dio Brando. This leads to all of the events of
parts before part 7.
The ability in parts 1 and 2 is called "Hamon", or "Ripple".
This ability gets forgotten by the time part 4 comes around.
Joseph Joestar, grandson of Jonathan Joestar, is a very laid
back 18 year old British American featured in part 2, Battle
Tendancy. He is shown as being very confronational, and
usually doesn't think before acting. He also loves to provoke
his enemies.
Despite these features, he is very caring to his family and
friends, and loves befriending people.
Joseph appears in 2 parts besides his own, he appears in part
3, Stardust Crusaders, and part 4, Diamond is Unbreakable.
(he also hates the Japanese)
During his part, Stardust Crusaders, Jotaro Kujo is a 17 year
old delinquent in Japan. Due to his hair looking like it's
connected to his hat, there have been many memes about his
hat.
He can easily keep his cool when under stessful situations,
and usually expresses himself in short phrases. His most
iconic phrase is "Yare Yare Daze", which means "Good Grief" in
Japanese.
At this point there is a new power called "Stands" which is
suppose to be the manifestation of one's soul, and only stand
users can see other stands.
Jotaro's stand is called Star Platinum, who's main ability is
being a really STRONK punchy ghost.
Jotaro appears in 4 parts, part 3, Stardust Crusaders, part 4,
Diamond is Unbreakable, part 5, Golden Wind, and part 6, Stone
Ocean.
Josuke Higashikata is a first-year high schooler with a kind
heart, but also becomes goes into a blind rage when someone
talks down about his hair. He appears in part 4, Diamond is
Unbreakable.
Josuke's stand ability is called Crazy Diamond (or Shining
Diamond for the localized version). Just like Star Platinum,
it's another really STRONK punchy ghost, but
also has the ability to restore anything but himself to its
original state.
He is also never seen again in other parts.
Giorno Giovanna is technically a Jojo who lives in
the country of Italy. He appears in part 5, Golden Wind.
Giorno is a very kind person, but is also unforgiving toward
anyone who he thinks of as a scum.
Giorno's stand is called Golden Experience (or Golden Wind for
the localized version). His stand doesn't have as much power
as the previous 2 protagonists, but it has the ability to turn
any inanimate object into a living creature.