The term 'King of Rock and Roll' is often used to refer to the iconic singer Elvis Presley. Elvis was known for his unique style of music, which combined elements of rock, blues, gospel, and country. His influence on popular music is still felt today. The crossword solutions for this term are ELVIS (5 letters) and ENVY (4 letters). Elvis was so successful and influential that many other musicians envied him, making ENVY an appropriate solution for this term.