Theme overrides for custom hook_theme() in Drupal 7 I have a custom D7 module which defines it's own hook_theme() which defines a few theme functions, of which they define their own template, for example:

function foo_theme($existing, $type, $theme, $path) {
    $items = array(
        'post_foot' =&gt; array(
            'template' =&gt; 'templates/post_foot',
            'variables' =&gt; array('node' =&gt; (object)array())
        )
    );
    return $items;
}


As you can see, it defines it's own template, which is located in the foo module, in this specific case sites/all/modules/custom/foo/templates/post_foot.tpl.php

I'd like to be able to define my own post_foot.tpl.php in my theme, and use foo's tpl as a fallback.

Does this happen automagically? Do I need to expand my hook_theme() to include overrides?
This should happen automatically. Most core modules define theme hooks which you wouldn't think twice about overriding in your theme. Take a look at node_theme for example http://api.drupal.org/api/drupal/modules--node--node.module/function/node_theme/7.

The devel themer module should help you out with such things. Needs some work for D7 but should help.