I used to work for a mediocre publisher that did a lot of tv-to-book stuff, like novels written by the (fictional character) Richard Castle from the tv show Castle, etc. Those Castle books, at least the first couple, were best sellers so some people in leadership got it into their heads that this was a cash cow. But most of those kinds of projects didn't do well or never even got off the ground, At one point we were meeting with Proctor and Gamble and an ad agency that worked with them talking about creating a "novel" (and potential series!) written by a character from Old Spice commercials. Honestly the whole thing was fucking embarrassing, luckily everyone realized after the first couple proposals that this was a terrible idea and the whole thing was dropped. Unless they later went to another publisher and actually did this shit, but I'm guessing not because the "virality" of those particular commercials dried up real fast.