A person who takes over a role, position, tradition, or property from a predecessor.
He was named as the successor to the company president.
It is important to nurture successors for traditional culture.
相続人 is a legal term for an heir who inherits property or assets. 継承者 is broader and can refer to inheriting roles, traditions, or abstract things.
Compound of 継承 (keishō, 'inheritance, succession') + 者 (sha, 'person'). The kanji 継 means 'inherit, succeed', 承 means 'receive, take over', and 者 means 'person'.