Also while a title can't be copyrighted and you can have Harry Potter, the seedy detective (because the names are only copyright in context), there may be be valid Registered Trademarks, such as Disney, Batman.
But pre-existing phrases such as "Winter is coming" can't be protected, despite what the studio says. Also while copying the actual DC Superman would be plagiarism, the name is a weak trademark because it exists in multiple books before Detective Comics registered it. OTOH the USA Apple Inc, formerly Apple Computer Inc lost cases to the Beatles multiple times, as they deliberately picked the name invented by the Beatles, Apple Corp, with a bitten Apple logo, though Beatles' logo was a core and Apple Computer had one bite (the Apple 1 & 2 had 1 byte cpu
). One settlement was that they would not sell music. You can reuse a trademark in a different context. Later Apple USA launched iTunes and lost another case. They also had to pay Cisco for iPhone (as it's a related field) and Fujitsu for iPad (umm, almost same product!).
Intellectual property can be complicated and big companies (Vogue, McDonald's, Coca-Cola etc) rely on bullying as much as real legal rights to attack unrelated companies, or something they think is too similar. Often the deepest pockets and US mega Corp in a USA court will win.
Then there are historic names. A new company could never be Royal Mail or Eircom (nor Eir which they are now), but these are privatised state entities and mysteriously allowed to keep the State name. Eir isn't even an Irish company (registered in Channel Islands for "tax") and Royal Mail may soon be owned by a Czech business.