William Ahern
William or Liam or Bill Ahern may refer to:
- Bill Ahern (footballer, born 1865), Australian rules footballer for Carlton
- Bill Ahern (footballer, born 1874), Australian rules footballer for St Kilda
- Liam Ahern, also known as William Ahern, Irish Fianna Fáil politician
- William Ahern (Medal of Honor), Irish-born American sailor
- Will Ahern, American vaudeville entertainer