The Marvel timeline is a complicated beast – just ask Disney. The studio behind the superhero movies has been struggling to tell viewers how to watch the Marvel movies in order having changed the chronological order.
As pointed out by ComicBook.com (opens in new tab), over on Disney Plus, Black Widow and Black Panther have switched positions on the streamer's chronological ordering of the Marvel movies. Originally, Black Widow came after Black Panther, but that has now been switched around with Black Panther taking place after Black Widow.
Why the initial error? Both movies take place between Captain America: Civil War and Avengers: Infinity War in the MCU's 2017. You could argue that Black Widow takes place slightly later than Black Panther as the movie finishes with the titular hero sporting the blonde hair she has imminently in Infinity War. Then again, Black Panther tells a longer story about king T'Challa fighting Killmonger.
Most likely, the events of the two movies take place simultaneously, and picking which one to watch first is simply personal preference. Black Widow arguably makes sense to watch later, as the movie was released four years after Black Panther (yes, really) but Disney has decreed otherwise, and who are we to argue with the House of Mouse? At least, until the timeline changes again...
Meanwhile, the Marvel universe is set to get a whole lot busier in the near future. For more, check out our guides to Marvel Phase 4 and all the new Marvel TV shows coming your way. The next movie will be Doctor Strange in the Multiverse of Madness, which looks set to break the multiverse even more.