You may have had too small of an enclosure, or had a species that's territorial or doesn't work in groups. Either circumstances can cause the hamsters to fight and kill each other.

It was a HUGE cage, several levels with plenty of activities. I just think he was evil.

The most common species of hamsters - Syrian - are not to be kept in together. You may see them as young hamsters in the same enclosure when they are being sold, which is misleading. They will fight sooner or later, as they are solitary animals, with the exception of possibly a female and male while she is in heat. Otherwise, Syrian hamsters will fight and likely kill one another. Other smaller breeds may harm each other when they are not kept in appropriate conditions or do not get along with their roommate. Good living conditions for multiple hamsters is not about about how many activities are available - it is far more important to have square footage that allows them to spread out. Many of the "interesting" cages marketed in pet stores are actually not large enough. Tubes and towers and shelf levels do not add the square footage that many hamsters need to thrive and not fight.

I learned my lesson, I'll never own hamsters or rodents again. That traumatized me. The intestines everywhere looked like ramen noodles...ugh!

?Go Lemmiwinks, kill Wikileaks?

That is one badass hamster.

Wow that’s a whole new diy

I mean I feed him everyday and fill his water bottle so I guess that counts as dinner hahaha

Why can't I vote or reply directly to Richard's comment ?

Because we’re so awesome, there’s no need to mess with perfection! :)

Testis is the singular form. Testes* is the plural form.