Who played the reclusive scientist William Bell on the U.S. TV series "Fringe"?

The well known actor Leonard Nimoy made his final great TV appearance in the 2008 - 2013 Fox science fiction series "Fringe". In the series, he played reclusive scientist Dr. William Bell. He had just a handful of appearances in the series, including one that was an animated appearance. Nimoy's death as Bell in season 2 left a major impact on the show. Bell was needed and reemerged in seasons 3 and 4.

Leonard Nimoy as Dr. William Bell was Dr. Walter Bishop's former lab partner, the founder of Massive Dynamic (a biotechnology development company). Bell was apparently killed in the finale of season 2. Leonard Nimoy, who had retired from acting after season 2, agreed to continue to provide the voice of William Bell. Subsequently, Bell's reappearance via an animated character occurs in season 3. In season 4, Bell reappears after a plot timeline is altered.