X series or xSeries or Series-X may refer to:

• X (video game series), a space combat and trading game series
• X the album, a series of Christian rock compilation albums
• X-Men (film series) or "X" films

• Fujifilm X series, a series of digital cameras
• Nokia Xseries, a family of mobile phones.
• Sony Ericsson X series, a series of cell phones
• Xbox Series X, a videogame console from Microsoft

• eServer xSeries, of the IBM System x
• Intel Core X-Series, a series of computer CPUs
• ThinkPad X series, of laptops
• Northgate SeriesX, a line of computers from Northgate Information Solutions
• Sony Vaio X series, a series of laptops

• BMW X-series vehicles, see List of BMW vehicles
• X-planes, a series of US experimental aircraft
• Yamaha's X-series motorcycles

• X (disambiguation)