 In addition to the regular cast , episodes feature guest voices from many ranges of professions , including actors , athletes , authors , musicians , and artists . Recurring guest voices include : Ernest Borgnine , who voiced Mermaid Man from 1999 until his death in 2012 ; Tim Conway as the voice of Barnacle Boy ; and Marion Ross as Grandma SquarePants . Notable guests who have provided vocal cameo appearances includes David Bowie as Lord Royal Highness in the television film Atlantis SquarePantis , Johnny Depp as the voice of the surf guru , Jack Kahuna Laguna , in the episode " SpongeBob SquarePants vs. The Big One " , and Victoria Beckham as the voice of Queen Amphitrite in the episode " The Clash of Triton " . 
