If we apply the term retroactively IMO the first SUV would be the Chevrolet Master or Suburban. Started off 1933/35 and it was a station wagon body on a 1/2 ton truck frame.

If we add off-road capability to the requirements, IMO still the Suburban which gained 4x4 in 1955. Next would be the J50 Land Cruiser, first of the "station wagon" line that came out in 1967.