Samsung has unveiled a new line of TVs in South Korea recently. However, rather than being mere flat content-displays, this new line is apparently designed to fit into the 'millennial' lifestyle. To this end, one of them, the Sero, can be switched between horizontal and vertical orientations.
https://www.notebookcheck.net/The-Sero-is-a-new-TV-by-Samsung-that-can-go-into-portrait-mode.419977.0.html