Not since he became such a prominent character. He made tons of guest appearances in cartoon shows (I swear, his main job for the last 20 or so years of his life was voicing himself in animated shows!) but in Family Guy he had a far more major role. Out of his most recent work, I think this is the show that'll suffer the most without him.

True, I love Adam just as much as most the characters on the show. Hope they do an epic tribute for his work.