Replace the Default Anonymous Avatar on Blogger Comments
Step 1. Go to Dashboard - Template - click on the Edit HTML button
...click anywhere inside the code area and open the template search box by pressing the CTRL + F keys
Step 2. Type or paste this code in the search box, then hit Enter to find it:
</body>Step 3. Just above the </body> tag, add the following code:
<script src='http://code.jquery.com/jquery-latest.js'/>Step 4. Save the changes by clicking on the Save Template button
<script>
$("img[src='http://img1.blogblog.com/img/anon36.png']")
.attr('src', 'https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjoJxhp4SeRHdPFibwaFDj48diugSYjtXhooFZtIcyJK9KUWlvzHSOeOpD9DXMU3bFfASJE1S2JtbR1mp0JpDEdyULQ5CMuQsoWQ-SGLlx34i_P4cLonf1qYkoz0o7RExKuudsKQYWobV4/s1600/default_avatar.gif')
.ssyby('blank')
</script>
<script src='http://code.jquery.com/jquery-latest.js'/>
<script>
$("img[src='http://img2.blogblog.com/img/b36-rounded.png']")
.attr('src', 'https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg8Mtat21VhqFncG1nwjc0k52QJYdRpYdkQj4q-w4UM9jlXHTXW3u4nknocje3zCbP1tFjB_e_iF1XFci-qNtWP2vG90fv9FgwgZ_4o3rE_GFK89OtbFWGHD4B7a2zlHzYQzA_-cvFXCAE/s1600/blogger-user.png')
.ssyby('blank')
</script>
Changing the default avatar
For Anonymous users: Replace the code in red with your image addressFor Blogger users: Replace the URL in blue with your own.
You can choose an avatar from here and then copy the url of it:

https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjoJxhp4SeRHdPFibwaFDj48diugSYjtXhooFZtIcyJK9KUWlvzHSOeOpD9DXMU3bFfASJE1S2JtbR1mp0JpDEdyULQ5CMuQsoWQ-SGLlx34i_P4cLonf1qYkoz0o7RExKuudsKQYWobV4/s200/default_avatar.gif

https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhr8RsYWHnbwyF-lLWeWMYSHkM7cTqXVCoAOpwLs-bOdfcZnIRbYPmdk01OJGNEAjZUTfQTBXjVyjiPXmRxqxCImJlISxb8J9yPavdVjujjSou4mQYBB6D6__QB6G52T2yTBSC1iBNbN1s/s1600/facebook.gif

https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiYJKcAOzrx-X189D4AgBcih2zqr6t_M23zAwmv4cA96onMiWDDkGlh1cueQgh3Qc60bYv5shdVKkxYHddWUYhZLDarHezRcSrESD8CHI5hGnSilma4EJ1FEPl2RCv_N8pODG4JOiSGX6Q/s1600/anonymous3.png

https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhM4HBZhMi-jAOTuURWCTfRNFBbVNJXQLLLjw-xy_BOA6Ez-C31RY7iZReMyiSGUaohetwZQ-XwSZjefCEtf2lerJrvC-5WRfMHwAT5eqUsO_cCQnkZn3OWejM4oTdTTvpUrGiqymseCAdf/s1600/blogger-user.png
That's it! If you found this trick useful, please consider sharing it.
Make use of Smilleys Codes