cron.php in core/cron.php

Handles incoming requests to fire off regularly-scheduled tasks (cron jobs).

drupal_access_denied in core/includes/drupal.inc

Delivers an "access denied" error to the browser.

file_download in core/includes/file.inc

Page callback: Handles private file transfers.

page_example_arguments in modules/examples/page_example/page_example.module

A more complex page callback that takes arguments.

system_batch_page in core/modules/system/system.admin.inc

Default page callback for batches.

system_date_delete_format_form in core/modules/system/system.admin.inc

Menu callback; present a form for deleting a date format.

user_pass_reset in core/modules/user/user.pages.inc

Menu callback; process one time login link and redirects to the user page on success.

views_plugin_display_page::execute in core/modules/views/plugins/views_plugin_display_page.inc

The display page handler returns a normal view, but it also does a backdrop_set_title for the page, and does a views_set_page_view on the view.