someone who takes a job or position previously held by someone else [↪ predecessor]:
His successor died after only 15 months in office.
I'm sure she will be a worthy successor (=someone who is very good and deserves to be someone's successor).
her successor to the post
Sloan will be Barrett's successor as treasurer.
a machine, system etc that exists after another one in a process of development:
the transistor's successor, the microchip