| Name | Alter Ego(s) | Original Publisher | First Appearance | Year | Date | Writer | Artist |
|---|
| X' Hal | | DC Comics | The New Teen Titans, Vol. 1, #24 | 1982 | October | Marv Wolfman | George Pérez |
| X-21 | Superwoman Robot | DC Comics | Action Comics, Vol. 1, #333 | 1966 | February | Leo Dorfman | Jim Mooney |
| X-24 | Pantha and Rosabelle Mendez | DC Comics | The New Titans, Vol. 1, #73 | 1991 | February | Marv Wolfman | Tom Grummett |
| X-2-Y | Dick Malvin | DC Comics | Action Comics, Vol. 1, #344 | 1966 | December | Jim Shooter | Jim Mooney |
| G-5 | Quality Comics | Hit Comics, Vol. 1, #1 | 1940 | July | Will Eisner | Charles Sultan |
| X | | Quality Comics | Military Comics, Vol. 1, #1 | 1942 | March | Vernon Henkel | Vernon Henkel |
| Xadu, Doctor | | DC Comics | Adventure Comics, Vol. 1, #283 | 1961 | April | Robert Bernstein | George Papp |
| Xanna | | Gorilla Comics/DC Comics | Empire, Vol. 1, #1 | 2000 | May | Mark Waid | Barry Kitson |
| Xanthi | | DC Comics | New Titans, Vol. 1, #51 | 1989 | January | Marv Wolfman and George Pérez | George Pérez |
| Xardo | | DC Comics | Action Comics, Vol. 1, #325 | 1965 | June | | Curt Swan |
| Xasnu | | DC Comics | Action Comics, Vol. 1, #278 | 1961 | July | Jerry Coleman | Curt Swan |
| Xavier, Charles | Doctor Strangefate | DC Comics/Marvel Comics | DC Versus Marvel Comics, Vol. 1, #3 | 1996 | February | Ron Marz and Peter David | Dan Jurgens and Claudio Castellini |
| Xax (I) | Green Lantern of Space Sector 3500 | DC Comics | Green Lantern, Vol. 2, #9 | 1961 | December | John Broome | Gil Kane |
| Xax (II) | Green Lantern of Space Sector 3500 | DC Comics | 52, Vol. 1, #31 | 2006 | December | Grant Morrison, Geoff Johns, Mark Waid and Greg Rucka | Freddie E. Williams II |
| X-Bomb Betty | | DC Comics | Legionnaires, Vol. 1, #2 | 1993 | May | Mary Bierbaum and Tom Bierbaum | Chris Sprouse |
| Xebel | | DC Comics | Aquaman, Vol. 1, #11 | 1963 | September | Jack Miller | Nick Cardy |
| Xeen Arrow | | DC Comics | Adventure Comics, Vol. 1, #253 | 1958 | October | Dave Wood | Jack Kirby |
| Xenofobe | | DC Comics | Superman, Vol. 1 #295 | 1976 | January | Curt Swan | Elliot S! Maggin |
| Xeo | | DC Comics | Detective Comics, Vol. 1. #260 | 1958 | October | | Sheldon Moldoff |
| Xera | Xera Kharindot | DC Comics | Legion of Super-Heroes, Vol. 3, #32 | 1987 | March | Paul Levitz | Greg LaRocque |
| Xero | Coltrane "Trane" Walker | DC Comics | Xero, Vol. 1, #1 | 1997 | May | | ChrisCross |
| Xiang-Fa | | DC Comics | Green Lantern, Vol. 3, #19 | 1991 | December | Gerard Jones | Mart Nodell and Romeo Tanghal |
| Xiuhtecutli | | DC Comics | Justice League International, Vol. 2, #63 | 1994 | April | Gerard Jones and Will Jacobs | Chuck Wojtkiewicz |
| | Warner Bros. Animation | Teen Titans (TV series) | 2004 | August 28 | | |
| Xola Aq | White Witch, Mysa Nal, Hag, Jewel and Black Witch | DC Comics | Adventure Comics, Vol. 1, #350 | 1966 | November | E. Nelson Bridwell | Curt Swan |
| Xolotl | | DC Comics | 52, Vol. 1, #21 | 2006 | September | Geoff Johns, Grant Morrison, Greg Rucka and Mark Waid | Keith Giffen and Joe Bennett |
| Xombi | David Kim | Milestone Media | Xombi, Vol. 1, #0 | 1994 | January | John Rozum | J.J. Birch |
| Xotar | Weapons Master | DC Comics | Brave and the Bold, Vol. 1, #29 | 1960 | May | Gardner Fox | Mike Sekowsky |
| Xov | | DC Comics | Action Comics, #242 | 1958 | July | | Howard Sherman |
| XS | Jenni Ognats | DC Comics | Legionnaires, Vol. 1, #0 | 1994 | October | | Jeff Moy |
| Xylpth | Green Lantern of Space Sector 151 | DC Comics | Green Lantern, Vol. 2, #151 | 1982 | April | Paul Kupperberg | Carmine Infantino |
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