Dennis Quaid threw a block party Saturday … and a legendary musician provided essential backup.

Dennis, whose job description can fairly read, “Actor/Musician,” had all the trappings for his Brentwood neighbors … food, drink and music.

Dennis and his band performed, with a special guest … Robby Krieger from The Doors played guitar for the blues and rock set.  Robby and Dennis aren’t strangers … they’ve played together before.

Dennis’ fiancee, Laura Savoie, was cheering with approval from the sidelines.

The bad news … not a lot of masks or social distancing, and California has seen a big uptick in COVID-19 cases.