Definitive proof that Tom Cruise wasn't the first really tiny US secret agent...

...and I believe that Cruiser is slightly taller (by about 4ft 10in) than the hero of the 1959 science fiction/spy series World of Giants (which was also known by the acronym W-O-G - no, honestly). You can see the opening sequence of the series right at the start of this compilation:

In case you're wondering what a six inch spy looks like...

I've no idea whether that giant of the SF and horror genres, Richard Matheson, who wrote the novel The Shrinking Man as well as the script for the 1957 film adaptation, The Incredible Shrinking Man, received any royalties from the TV series - but he deserved to.