Electromagnetic Spectrum

[Deronius]

I always wanted to know if there was any ray stronger than a gamma ray?
I heard of things called cosmic rays that come off of stars, but I don't know if it is true or not?

[RobJim]

I believe gamma rays are the electromagnetic rays with the most energy.

http://imagers.gsfc.nasa.gov/ems/gamma.html

Cosmic rays are not electromagnetic radiation.

http://en.wikipedia.org/wiki/Cosmic_rays

I don't know what you mean by "stronger". I don't know which carries more energy if that's what you mean.

[Deronius]

I think I meant to say higher energy, but if they are not EMR then what are they?

[RobJim]

They are a mixture of particles and gamma rays. Take a look at the Wikipedia article I linked.