predecessor

noun3

1. •
   One who precedes; one who has preceded another in any state, position, office, etc.; one whom another follows or comes after, in any office or position.

   • I thought about my predecessor, who had died of drink and smoke; and I could have wished he had been so good as to live, and not bother me with his decease. — 1849
2. •
   A model or type of machinery or device which precedes the current (or later) one. Usually used to describe an earlier, outdated model.

   • The steam engine was the predecessor of diesel and electric locomotives.
3. •
   A vertex having a directed path to another vertex