During season 3 of Spider-Man & His Amazing Friends, Stan Lee thought it might be a good idea to mark the X-Men's 20th anniversary by having the team appear on the show. One quibble. The Native American Thunderbird had been killed off in the comics well before this point, and so his inclusion, one must assume, would be in answer to the Super Friends' Native American hero, Apache Chief, as if to say, we did it first.
When Marvel decided to revive the X-Men in the comics in the mid-70's, they did make them more globally diverse, with Canada (Wolverine), Ireland (Banshee), & Africa (Storm) represented. The Japanese mutant, Sunfire, briefly joined the team, but, like Wolverine & Banshee, he wasn't new, having previously appeared in Sub-Mariner. So it can be said that DC & Hanna-Barbera responded with Apache Chief, Samurai, & Black Vulcan being added to the Super Friends, despite the haterizing that would follow years later. I digress.
Warp to 1983. While some members of the X-Men's original team had appeared on The Marvel Super Heroes Show some years earlier, this was the first appearance of the more popular incarnation introduced in 1975 on TV. The plot sees a former boyfriend of Angelica Jones, aka Firestar (Kathy Garver, ex-Family Affair), now a cyborg known as Cyberiad, attack the Spider-Friends and the X-Men in the latter team's own Danger Room. The idea is that Angelica was originally an X-Man, but that wasn't really the case.
After production on Amazing Friends had ended, Marvel decided to bring Firestar into the Marvel Universe proper in a 4-issue miniseries produced in 1984. She would eventually join the Avengers instead of the X-Men, but hasn't been seen in years.
In 1989, the X-Men would return to TV in an ill-fated, but well-received pilot. Unfortunately, it would be 3 more years before they'd get their own show, which we've previously discussed. We will serve up Pryde of the X-Men real soon, so you can judge for yourselves.