Originally Posted by Wikipedia
In Uncanny X-Men #153, Kitty Pryde the teenaged member of the X-Men, told a bedtime story to Illyana Rasputin, who was living with the X-Men at the time. The story recast the X-Men, including the recently deceased Phoenix in the roles of fairy tale characters. One such character was the dragon "Lockheed", who was based on the modified SR-71 Blackbird jet aircraft used by the team. The name originates from the Lockheed Corporation, makers of the Blackbird.
Not long after, the X-Men were kidnapped into outer space by the alien Brood. Inside the Brood starship, Kitty discovered an extra-terrestrial dragon who resembled the creature from her fairy tale except that he was the size of a cat. He saved her from the Brood and then departed with her, leaving behind his fiancée who he was due to wed the following day. She tried to hide his presence from Professor X and her teammates but he was revealed back on Earth when he again saved her life, this time from a nest of alien Sidrian hunter hatchlings. The X-Men accepted his presence in the X-Mansion and has since been Kitty's longtime companion.
During the Secret Wars miniseries, the X-Men including Lockheed were transported to an alien planet, where Lockheed met a female alien dragon. This second dragon accompanied Lockheed and his allies to Earth, but she grew to gigantic size upon arrival, rampaged across Tokyo and was apparently killed, though the dragon has resurfaced recently. In addition to serving alongside Kitty with the X-Men, he joined her when she founded the British superhero team Excalibur.
An alternate reality's counterpart of Lockheed served as Excalibur's means as interdimensional transport during the "Cross-Time Caper" storyline; this larger, female Lockheed eventually departed with Excalibur's sometime foes, the Technet after having mated with their member Numbers and giving birth to his children. Lockheed made few appearances following the departure of writer/artist Alan Davis from the Excalibur series; later issues suggested that he had simply gone into hiding and had stayed away because he disapproved of Kitty's then-boyfriend, Pete Wisdom, though he did once save Wisdom's life. Lockheed started appearing more frequently after Kitty left the X-Men to go back to college. After she returned the team, he joined her. When the X-Men were battling the alien Ord, it was Lockheed who saved the day by burning Ord.
Both Kitty and Lockheed are currently appearing in the pages of Astonishing X-Men.