As per his official Facebook page:

Colonel Meow passed away yesterday evening. I will post more about the details when I've had a few days to grieve. Thank you so much for your understanding, Minions. Your love and support has meant the world to us both. -Slave Beast

This is depressing. =( RIP Colonel Meow.

I feel so pathetic over the fact that I cried a little when I saw the post on my facebook page, and that it kind of ruined my evening. Colonel Meow was a rather famous internet cat, and I'll miss seeing that ridiculously fluffy face in my news feed.

How sad. Rest in peace Colonel Meow. Thanks for the laughs

I never heard of Colonel Meow. O.o But honestly, that picture is more grumpy than the grumpy cat. What was this cat famous for? :o

I'm gonna miss that big fluffball. :(

Same here. My heart dropped and I died a little inside. =( If Grumpy Cat goes too, I'm done with the internet forever.

I loved seeing his posts.

Wikipedia He holds the record for the longest hair on a cat, and his followers were referred to as minions.

How ironic that you're here... O.o But in all reality, me too.

I'm sure Grumpy Cat will live longer, Colonel Meow had a heart problem.

Me too. Tarder Sauce aka the Grumpy Cat is still my favorite. But Col. Meow brought many smiles to my face.

Aww! RIP Colonel Meow!

He's cute D: R.I.P Meow. Can't believe I've never heard of him though, pretty sure I've seen him around before though.

Nooo! That's too sad, I don't know how I'm going to deal with my evening, may you be in a wonderful place Meow, you will be missed by too many internet cat people.