Possible Clues:

• Comedian Williams
• William of 'Carrie'
• Nicky of 'Boston Public'
• ''The Greatest American Hero'' star
• Good last name for a veterinarian
• William of "Carrie"
• William of TV's 'The Greatest American Hero'
• Actor William of 'The Greatest American Hero'
• Nicky of ''Boston Public''
• 'Boston Public' actor Nicky