I wish I could give you more, but I can definitely give you three. The first issue of the new "X-Men," comic was introduced in 1975. "X-Men" had previously been around more than a decade, but here entirely new characters were introduced. X-Rated movies were also a big deal in the 1970s. Remember, we had no VCRs so people had to go see "Deep Throat" in the theater. This activity was first endorsed by Truman Capote, who may have had little interest in the film himself but was important in society and so brought society people to see it. The third thing that starts with an X from the 1970s? Certainly one of the greatest punk bands, X-Ray Spex. For double points, this was also the name of Poly Styrene's clothing line.
Things in Texas that begin with X
· xylophone
x-ray
x-ray xenopus xenobian
70s
· xylophone
xylophone
vowels
x-ray images
x-ray machine at Antananarivo Hospital
xerxes
xylodromus xyletinus