I hope John is recognizable. Sherlock obviously is, but would you know John is supposed to be John if you only saw the picture with no mention of what fandom this userhead is for? Also, as much I like beige and I know people are pretty fond of the jumper, but I didn't want John to be monochromatic.

 

ETA: Now with even more info (see new table row)!
Edit (February 15, 2017): Now also with instructions for Dreamwidth.

CSS	This is the Sherlock code. For John just change 'Sherlock' to 'John' in the image URL. Go to Custom CSS and insert the code. .ljuser img { width: 0px !important; height: 0px !important; padding: 16px 0px 0px 17px !important; background: transparent url(http://fatfrog.info/Ma/A/Sherlock/userhead/Sherlock.png) no-repeat !important; }
user/comm	.ljuser img is the general code which changes the images of both, user and community. If you want the community image to be different from the user image, use .ljuser img[src*="userinfo"] or .ljuser img[src*="community.gif"] For Dreamwidth it's .ljuser img[src*="user.png"] or .ljuser img[src*="community.png"]
Where will the userhead appear?	It's not like the userheads LJ sells that will show in front of only your username, whatever journal you post in. The userhead will appear in front of every community and/or username (if it's both or just one of them, depends on which code you use [see the table cell above]) where your CSS reaches. You will see it on your journal, but not on your profile and - if you disabled customized comment pages - not on comment pages. You will see see it on other journals if you view them in your style (put ?style=mine at the end of the URL). Others will only see it when they go to your journal.

ETA: How to make your userheads work correctly