Let us just settle this one here and now. The answer depends on the particularities of the question being asked. What was the actual title of the 1941 Universal Studios classic starring Lon Chaney Jr.? It is THE WOLF MAN. “Wolf” and “Man” are two separate words. This would be fine, if they were hyphenated. They are not. Thus they are grammatically incorrect. So if you ever see anybody, me included, write it out as “Wolf Man” you can know that I or they are being historically accurate but grammatically correct.
If you want to use correct grammar, you need to combine the two words. “Wolfman.” Universal figured this out when they made the remake with Benecio Del Toro back in 2010. The difference in the titles also helps to distinguish between the two films. Even so, the English major in me can’t leave it go as “Wolf Man,” not even when referencing the original movie. I have to correct it. And, as is the case with THE TEXAS CHAINSAW MASSACRE, which was originally released as THE TEXAS CHAIN SAW MASSACRE with “chain” and “saw” separated as two different words, with the passage of time the grammatically corrected version has come to replace the original syntax. The correct word is “chainsaw”, one word, and the correct term is “Wolfman.” Either Curt Siodmak made a typo and nobody ever corrected it, or he was getting one over on succeeding generations when he broke the name of the monster up into two words.