Does LIKE support (or can you code for) an optional character in a string?

I'm doing some IIS log file analysis and trying to group by referrer. This is a challenge since you can have multiple prefixes for the same domain:

SELECT 
    CASE
        WHEN Referrer LIKE 'http%://microsoft.com/%' THEN 'Microsoft'
        WHEN Referrer LIKE 'https://microsoft.com/%' THEN 'Microsoft'
        WHEN Referrer LIKE 'http://www.microsoft.com/%' THEN 'Microsoft'
        WHEN Referrer LIKE 'https://www.microsoft.com/%' THEN 'Microsoft'
        WHEN Referrer LIKE 'http://social.microsoft.com/%' THEN 'Microsoft'
        WHEN Referrer LIKE 'https://social.microsoft.com/%' THEN 'Microsoft'
        ELSE 'Other'
    END AS MyGroup
    , COUNT(*)
FROM MyIISLog
WHERE 
    Referrer LIKE 'http://microsoft.com/%'
    OR Referrer LIKE 'https://microsoft.com/%'
    OR Referrer LIKE 'http://www.microsoft.com/%'
    OR Referrer LIKE 'https://www.microsoft.com/%'
    OR Referrer LIKE 'http://social.microsoft.com/%'
    OR Referrer LIKE 'https://social.microsoft.com/%'
GROUP BY 
    CASE
        WHEN Referrer LIKE 'http%://microsoft.com/%' THEN 'Microsoft'
        WHEN Referrer LIKE 'https://microsoft.com/%' THEN 'Microsoft'
        WHEN Referrer LIKE 'http://www.microsoft.com/%' THEN 'Microsoft'
        WHEN Referrer LIKE 'https://www.microsoft.com/%' THEN 'Microsoft'
        WHEN Referrer LIKE 'http://social.microsoft.com/%' THEN 'Microsoft'
        WHEN Referrer LIKE 'https://social.microsoft.com/%' THEN 'Microsoft'
        ELSE 'Other'
    END

Ideally this could be shortened to one line but I can't seem to figure out how to do it.

Just so as to head off any questions, this won't work:

WHEN Referrer LIKE 'http[s]://microsoft.com/%' THEN 'Microsoft'

This will match https:// only; it won't match on http://

And this just leads to possible garbage results:

http%://microsoft.com/%

This would match on anything that started with "http" and contained "://microsoft.com/" - "https://someotherdomain.net/somepage.php?://microsoft.com/" would match (which is not what I want).

Any suggestions? I tried searching but the search engines keep thinking I'm trying to find optional parameters (which is not what I want).

A regex example of what I want is like this:

^https?\://(([^.]+)\.)?microsoft\.com

I know that LIKE isn't akin to regular expressions but it sure would be nice if I could simplify my currentlywaytoolong CASE and WHERE clauses.

Thank you

EDIT - In this example, I've only used a single domain (microsoft.com). However in my real world use, I need to support multiple domains in the same query (microsoft.com, google.com, yahoo.com, etc) and their variations.