Cosmo from Fuller House At just four years old, Cosmo from Fuller House passed away from surgery complications. In addition to playing the family's dog (who was supposed to be the great-grandson of Comet from Full House), Cosmo also appeared on Suits, The Middle, and Grey's Anatomy. In September 2020, the Tanner family reunited to perform Jeff Franklin's original song, "Gotta Love a Golden," to honour Cosmo and Comet. Image Source: Everett Collection