| X Window selection | X Window System | X window system |
| X Window system | X Window System core protocol | X window system desktop environment |
| X Window System desktop environment | X Window System protocols and architecture | X Windowing System |
| X Windows | X windows | X wing |
| X wing alliance | X With U | X with U |
| X woman | X woman (disambiguation) | X Women |
| X World Youth Day | X Worship 2006 | X Worship 2007 |
| X Wrestling Alliance | X Wrestling Federation | X x |
| X X | X X (band) | X X (EP) |
| X X (Loona EP) | X X (song) | X X X |
| X X X (disambiguation) | X X X (L'Arc-en-Ciel song) | X X X (song) |
| X Y | X Y & Zee | X Y & Zee (song) |
| X Y problem | X You | X Z |
| X Zone | X ~Dame~ / Crazy Rainbow | X ~Dame~/Crazy Rainbow |
| X! | X!NK | X!nk |
| X&Y | X&Y (album) | X&Y (Caity Baser song) |
| X&Y (film) | X&Y (song) | X' |
| X' theory | X'box | X'box (Yucatán) |
| X'chll'at-aa | X'ed Out | X'Eye |
| X'IAN | X'ian Palace | X'ianity |
| X'mas | X'Mas | X'Mas Chihuahua |
| X'mas Collections II | X'Mas Rave Fever | X's |
| X's & O's | X's & Oh's | X's & Ohs |
| X's & ohs | X's & Os | X's & os |
| X's (album) | X's (Cigarettes After Sex song) | X's (disambiguation) |
| X's (song) | X's and o's | X's and O's |
| X's and O's (disambiguation) | X's and Oh's | X's and Ohs |
| X's and ohs | X's and Os | X's and os |
| X's Face | X's on Trees | X's usage |
| X's World Tour | X'tabai | X'tina |
| X'ting | X'Trapolis | X'TRAPOLIS |
| X'Trapolis 1.0 | X'Trapolis 100 | X'trapolis 100 |
| X'Trapolis 2.0 | X'Trapolis 2.0 (Train) | X'Trapolis Cityduplex |
| X'Trapolis Mega | X'Trapolis Tsíimin K'áak | X'Trapolis Tsíimin K’áak |
| X'unéi | X( | X(3872) |
| X(4274) | X(4500) | X(4700) |
| X(5568) | X(HTML) | X) |
| X*Press X*Change | X++ | X+rays |
| X+Y | X+Y (film) | X+Y problem |
| X+Y sorting | X, a fabulous child's story | X, Author of Nothing, and Properly Represented by the Above Unknown Quantity |
| X, formerly known as Twitter | X, formerly Twitter | X, George |
| X, Inc | X, Inc. | X, inc. |
| X, Maria | X, Mike | X, the Eliminator (Birdman episode) |
| X, The Exterminator | X, the Exterminator (Birdman episode) | X, The Life and Times of Malcolm X |
| X, the movie | X, William | X, Y & Z |
| X, Y & Z: The Real Story of How Enigma Was Broken | X,inc | X,Inc. |
| X,y coordinates | X,Y, and Zee | X-0 |
| X-1 | X-1 (console) | X-1 (disambiguation) |
| X-1 Submarine | X-1 submarine | X-1 Viper |
| X-1 X-ray source | X-10 | X-10 Graphite Reactor |
| X-10 graphite reactor | X-10 Pile | X-10 Reactor |
| X-100 | X-100 (house) | X-100 (San Mateo, California) |
| X-101 | X-101 (disambiguation) | X-102 |
| X-103 | X-11 | X-12 |
| X-12-ARIMA | X-13 | X-13 Vertijet |
| X-13ARIMA-SEATS | X-14 | X-15 |
| X-15 (band) | X-15 (disambiguation) | X-15 (film) |
| X-15 Flight 138 | X-15 Flight 143 | X-15 Flight 150 |
| X-15 Flight 153 | X-15 Flight 174 | X-15 Flight 188 |
| X-15 Flight 190 | X-15 Flight 191 | X-15 Flight 197 |
| X-15 Flight 3-65-97 | X-15 Flight 35 | X-15 Flight 62 |
| X-15 Flight 77 | X-15 Flight 87 | X-15 Flight 90 |
| X-15 Flight 91 | X-15A-1 | X-15A-2 |
| X-15A-3 | X-15A2 | X-16 |
| X-16 (aircraft) | X-17 | X-18 |
| X-1800 | X-19 | X-1999 |
| X-1A | X-1B | X-1C |
| X-1D | X-1E | X-1R |
| X-1R Firecracker 200 | X-1R Pro Cup Series | X-2 |
| X-2 (film) | X-2 Counter Espionage Branch | X-2 Dragonfly |
| X-2 Shinshin | X-2 Skycycle | X-20 |
| X-20 Dyna Soar | X-20 Dyna-Soar | X-20 DynaSoar |
| X-20 Dynasoar | X-200 mine | X-21 |
| X-21A | X-22 | X-23 |
| X-23 (2010 series) | X-23 (2018 series) | X-23 (comic book) |
| X-23 (film) | X-23 (Laura Kinney) | X-23 (one-shot) |
| X-23 (X-Men: Evolution) | X-23 PRIME | X-23: Innocence Lost |
| X-23: Target X | X-24 | X-24 (comics) |
| X-24 (Logan) | X-24 engine | X-248 |
| X-248 Altair | X-24B | X-24C |
| X-25 | X-26 | X-26 Frigate |
| X-27 | X-28 | X-28 Sea Skimmer |
| X-29 | X-29 (airplane) | X-29 airplane |
| X-3 | X-3 (code) | X-3 code |
| X-3 Stiletto | X-3 Warrior | X-3,C-60Z |
| X-30 | X-30 NASP | X-30 National Aero-Space Plane |
| X-30 National AeroSpace Plane | X-30 National Aerospace Plane | X-30 Orient Express |
| X-301 | X-302 | X-303 |
| X-31 | X-31 missile | X-32 |
| X-33 | X-34 | X-35 |
| X-35 (yacht) | X-35C | X-36 |
| X-360 | X-360 (console) | X-37 |
| X-37 Future-X | X-37 OTV-2 Flight 1 | X-37B |
| X-37B Orbital Test Vehicle | X-37B OTV-1 | X-37B OTV-2 |
| X-37B OTV-3 | X-38 | X-38 Crew Return Vehicle |
| X-39 | X-4 | X-4 Bantam |
| X-4 missile | X-4 satellite | X-40 |
| X-405 | X-41 | X-41 (yacht) |
| X-41 Common Aerial Vehicle | X-41 Common Aero Vehicle | X-42 Pop-Up Upper Stage |
| X-43 | X-43A | X-43A Hyper-X |
