Possible Clues:

• Robert of "I Spy"
• Cosby's 'I Spy' co-star
• 'I Spy' co-star
• Cosby's "I Spy" costar
• Actor Robert of 'I Spy'
• Robert of 'I Spy'
• Cosby's "I Spy" co-star
• "I Spy" co-star
• Star of TV's "Trackdown"
• Late actor Robert of 'I Spy'