Jonathan Joestar is the first "JoJo" in the long-running manga JoJo's Bizarre Adventure. A nineteenth-century English nobleman, his rivalry with Dio Brando forms the core of the first arc, Phantom Blood. His father George had adopted Dio following the death of Dio's father, Dario. However, this act of kindness only resulting in suffering for Jonathan, as Dio went about methodically destroying Jonathan's life while also doing everything he could to get in George's good graces and be declared successor to the estate.
When George perishes while under Dio's care, Jonathan finds evidence that Dio had actually murdered him with poison, and that Dio had in fact used the exact same ploy to murder his own father Dario. After Dio dons the Stone Mask, turning himself into a vampire, Jonathan attempts to kill Dio by burning down the Joestar estate. However, Dio escapes.
Afterward, Jonathan comes across Will Anthonio Zeppeli, a master of Hamon (also known as Sendo or the Ripple); an ancient martial art that channels energy through breathing techniques and sunlight. Jonathan learns Hamon from Zeppeli, and later engages Dio in battle, supposedly killing him.
However, while on a cruise ship celebrating his honeymoon, Jonathan is attacked by Dio once more, despite the vampire being reduced to only his head. To stop Dio, Jonathan sinks the ship, allowing his wife and unborn child to escape. Jonathan loses his life with this final act.