[Opserty]

Hmm I'm not sure if there is a mod about. If no-one else posts then you can try this.

1. Create a new Plugin (AdminCP > Plugins & Products > Add New Plugin)
2. Set Hook Location to 'fetch_musername'
3. Use the following Plugin code:

PHP Code:

if($user['userid'] == 1)
{
    $user['musername'] = '<b>'. $user['username'] .'</b>';
} 


4. Change '1' to the userid of the person who's name you want to style.
5. Change the HTML in the single quotes to the markup you want.
6. Set "Plugin is Active" to Yes and hit Save.