From https://metaculus.com/questions/16011/star-trek-and-star-wars-crossover-before-2060/

Comparison of Star Trek and Star Wars is one of the largest topics of conversation among the science fiction fan base. Which of the two franchises is better is frequently debated among fans, and the two have a fair degree of influence on each other. The idea of a crossover film or TV program between the two franchises has been proposed since the first Star Wars film was released in 1977. Despite this, no such media has ever been produced.