As a little kid, when I first became interested in the Rams in the mid 50's the vaunted enemy was the Monsters from Midway. In the early 60's it was just about every other team because we couldn't beat any of the other teams on a predictable basis. What we could predict were losses!
In the mid 60's it was the Colts & Packers then later in the decade it included the Vikings.
In the 70's the 49ers, Cowboys & Vikings.
80's - 90's The usual suspects plus the Bears
'99 to present.....49ers, Pats, cowboys, 49ers, Patriots, Whiners, Cheatriots, whiner fans.