I assume by light rays, you mean visible light rays. In this case, gamma rays have shorter wave lengths.
UV, x-rays, gamma rays.
Gamma rays are of higher energy and much much shorter wavelength than visible light.
Yes, radio waves have a longer wavelength than visible light. They are part of the electromagnetic spectrum.
Both gamma rays and radio waves are part of the electromagnetic spectrum, but gamma rays are much higher frequency (shorter wavelength) than radio waves. Visible light is lower frequency than gamma and higher than radio.
The answer is Ultraviolet Waves. But really the shortest so far found is Gamma Rays. They are a million million million of those Gamma Rays going past you each minute. Ultraviolet rays are shorter than regular light that we see, but not shorter than Gamma Rays.
Radio and microwaves are longer than visible light. So are heat (infrared) waves. Ultraviolet waves are shorter than visible light. So are X-rays and gamma rays.
Microwaves
Light waves and X-rays are both forms of electromagnetic energy. X-rays, however, have higher energy (higher frequency and shorter wavelength) than (visible) light.
Radio and microwaves are longer than visible light. So are heat (infrared) waves. Ultraviolet waves are shorter than visible light. So are X-rays and gamma rays.
It is electromagnetic radiation, which is the same in composition as visible light but has a much higher frequency/shorter wavelength, and will do damage to any biological material it passes through. Both travel at the same speed ('velocity of light') but gamma radiation can penetrate material opaque to visible light.
Shorter wavelengths means higher frequency, and electromagnetic waves with higher energy. Beyond the blue end of the visible light you have ultraviolet rays; X-rays; and gamma-rays, in that order.
Waves the have a wavelength slightly shorter than the visible light are as follows: 1. Ultraviolet 2. X-rays 3. Gamma rays