There was that time that Thomas Magnum - star of TV's Magnum PI - met Jessica Fletcher - star of TV's Murder She Wrote.
It was a crossover caper. Part one aired as a segment of Magnum PI whilst the story concluded in a segment of Murder She Wrote.
Thanks to a disreputable source of mine, I've got hold of the TV Guide ads for some other lesser known crossovers from everyone's favourite elderly female detective (after Miss Marple).
She got about a bit, didn't she?