Showrunner is a thing, TV projects have them. They are the 'nexus' - both creative and a bit operational of the show. Like the 'founder' and 'visionary' of the show. They also kind of 'make the show happen'.
Dan Levy is the 'Showrunner' for Schitt's Creek.
Just type the name of your favorite TV show along with 'showrunner' and you'll see who it is.
Usually will be 'creator' and 'writer'. They will probably get a producer credit. Note that 'showrunner' is generally not a specific kind of 'credit' but that a feature 'credit' isn't really a title either. 'Exec. Producer' can mean anything. Or nothing.
The 'director' in TV is generally less important.
For film, usually the Director kind of plays that role as the lead visionary, especially if they pitched and raised the money, got the team together, got the actors to sign up etc..
Producers are generally not directly creative visionaries.
Q: Is "showrunner" an official title, or not?
EDIT: apparently not[0]:
"The highest ranking producer is the showrunner, the man or woman ultimately responsible for the creative direction of the series. Showrunner is a function, not a title — this person is credited as an Executive Producer. In many cases, he or she has “Created by” credit on the series"
[0] https://johnaugust.com/2004/producer-credits-and-what-they-m...
EDIT2: "A showrunner is the unofficial title given to the top-level creative decision maker and manager overseeing all episodes of an individual season of a television/episodic series. The showrunner is usually credited as an executive producer, producer and/or writer. "[1]
[1] https://help.imdb.com/article/contribution/filmography-credi...