Possible Clues:

• Seth of 'Late Night'
• "SNL" alumnus Seth
• Ari of 'Kate & Allie'
• Seth of "SNL"
• Longtime surname on late-night TV
• Seth of "Late Night"
• TV comic with a 'Jokes Seth Can't Tell' segment
• Seth of 'SNL'
• Seth with an NBC talk show
• Comedian Seth of "SNL"