Dragon Ball Z - Son Gohan: The Beast
Seven years ago, Son Goku sacrificed himself to defeat Cell, only for his sacrifice to be in vain when Cell resurrected himself. However, his son, Son Gohan, would finish the job, defeating Cell once in for all.
Perhaps in another timeline, Goku and Gohan would be reunited as father and son; however, on this version of Earth, Goku never comes back. Instead, Gohan is left to be the hero who protects Earth. Without his father to share the burden, Gohan acts as the rageful protector of Earth, using his anger as fuel to become stronger.
In Goku's absence, Gohan seeks power beyond a Super Saiyan two. In doing so, he discovers a special power within him that he calls 'Beast Ki'. This Ki is unique to Gohan and unlocks forms that he nor his father could have imagined.