Possible Clues:

• Honker in old comedy films
• Brother of Chico and Groucho
• ___ Productions (media company)
• Brother of Groucho
• Silent star of early talkies
• ''Selma'' production company
• Marx got American TV presenter aroused
• Silent clown
• Silent brother in "Duck Soup"
• Cheer up over-serious brother who never speaks