Some consider the 1931 Dracula starring Bela Lugosi to be the beginning of Universal Monsters while others consider a few films from their silent era to be included. It's hard to argue against the inclusion of Lon Chaney's iconic portrayal of The Phantom of the Opera, so instead of debating what should or should not be included in this list, I went ahead and put everything whether or not I agree with it myself as some aren't even horror films, but are linked to past Universal Horrors.
Here are some films that are Universal Horror Adjacent. Films that were bought by Universal Pictures that are often associated with Universal Horror, but are actually from another studio:
-Murders at the Zoo (Paramount)
-The Monster and the Girl (Paramount)