Change the wiki logo for a wiki without server access to set the logo image file path or upload access to the current logo image.

WikiLogo.js

/* **********************************************************************************
*                           MediaWiki logo replacer script
*     Author: Inquisitor Sasha
*     Contributors:
*
*     Developed for the Orain MediaWiki free wiki hosting service
*
* Replace the current logo of the wiki with your own logo image from anywhere
* Additionally, your can change the page that the logo image will link to,
* such as if your wiki uses a different main page title from the standard
* MediaWiki installation.
*
* ********************************************************************************* */

// Configuration settings

// Set this variable to the URL of any image that you want to use for your wiki logo.
// This should be in a stable location where it will not be deleted, moved, or overwritten
// This is the only setting you will need to configure, if your wiki name and virtual file path are conventional
var imgURL = 'https://upload.wikimedia.org/wikipedia/commons/thumb/c/c5/Eristalinus_quinquestriatus_02840.jpg/800px-Eristalinus_quinquestriatus_02840.jpg';

// You probably do not need to change anything past this point

// Set this to the title of the main page, as a URL style
var mainPageTitle = 'Main_Page';

// Set this to the virtual file path of the wiki.  Do not start with a slash.
// If you use domain.tld/Page_name configuration, just make this blank
var articlePath = 'wiki/';

// Script for inserting new logo into the wiki
// Do not change anything past this point unless you are comfortable with JavaScript and HTML!
logoID = document.getElementById('p-logo');
logoID.innerHTML = '<a href="/'+articlePath+''+mainPageTitle+'"><img src="'+imgURL+'" width="160px" style="position: relative; top: 10px"/></a>';

/* --------------------- End WikiLogo script --------------------- */