predecessor

noun

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.

   “(rare) ancestor (rare)”

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 Usually used to describe an earlier, outdated model.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. mathematicsA vertex having a directed path to another vertex

4. Something that precedes and indicates the approach of something or someone

   Similar: harbinger, forerunner, herald, precursor