Prolific Hollywood director and actor Rob Reiner, the mastermind behind 1980s classics “The Princess Bride” and “This Is Spinal Tap,” has been found dead in his Los Angeles home, NBC News said. He was 78.

Reiner was discovered Sunday alongside his wife, Michele Singer Reiner, and both appeared to have died from stab wounds, NBC News reported, citing a source close to the family. Police said earlier on Sunday they had found two people dead at Reiner’s house in the Brentwood neighborhood of Los Angeles, without disclosing their identities.

The son of legendary comedian and writer Carl Reiner, one of the pioneers of TV comedy in the 1950s, Reiner followed in his father’s footsteps winning bit parts in TV shows in 1960s. His breakout role came playing Archie Bunker’s liberal son-in-law Mike “Meathead” Stivic in the long-running comedy “All in the Family.”

Reiner branched out into film directing, helming classics such as “The Princess Bride,” an adventure fantasy, and “Stand By Me,” a coming-of-age film based on a Stephen King story.

Reiner co-founded Castle Rock Entertainment, which would go on to produce dozens of films including “When Harry Met Sally” and “A Few Good Men.”

Reiner continued acting. His most recent film release was “Spinal Tap II: The End Continues,” a sequel to his 1984 mockumentary about a washed up rock band.

He was also a well-known activist who contributed to liberal and Democratic causes.