Sam pixel icon

I´m doing some free icons for people on tumblr on my supernatural dogs blog [link]
I think i´m getting the hang of pixel art
still any critics and references would be great!
Rules
1-These are all free to use
2-No need to credit,though a link to the blog would be appreciated!
3-They´re all transparent,so if you want to add a background of your liking go ahead!just make sure the blog signature is still visible!
4-Besides adding a backgroud and changing its size you cannot change anything else in them.
5-You don´t have to ask to use
6-You may use them in whichever website you want
7-Have fun!
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(c)art & characterisation-me
(c)Sam winchester-notme