Are traditional vacuum tubes still used anywhere?

Maybe still some EMP-resistant radio front ends for military purposes. Magnetrons, TWTs and Klystrons for RF, including microwave ovens and industrial microwave sources.

Also ignitrons and hydrogen thyratrons, and, of course photomultipliers are widely used.

As Dave Tweed says below, solar-blind flame detectors (such as UVtron) are a current application.

X-ray equipment and radar sites as they, tubes, can handle the high power demands. As well as, of course, vintage ham equipment, radios, and TVs.

The are also used in guitar amplifiers. Most audio amplifiers work under the assumption that they do not color the original source audio in any way. The amplification should be transparent. Guitar amplifiers however, are built specifically to color the sound and tone in their own unique ways. Different types of tubes can achieve different sounds.


Vacuum Tube