forerunner in WordNet English dictionary

1. anything that precedes something similar in time
   "phrenology was an antecedent of modern neuroscience"
   antecedent  forerunner 
   
2. something that precedes and indicates the approach of something or someone
   harbinger  forerunner  predecessor  herald  precursor 
   
3. a person who goes before or announces the coming of another
   precursor  forerunner