Both Liverpool celebrities are buried at Allerton Cemetery, where the graves were devastated by jobs overnight.
The graves of Cilla Black and Sir Ken Dodd were defaced by vandals who are believed to have scribbled “offensive” graffiti on their tombstones.
Their families have been informed and work is underway to clean the gravestones.
A council spokesman said: “We were horrified to discover this morning that the graves of Cilla Black and Sir Ken Dodd had been vandalized overnight. The staff is in the process of making repairs.
Both families have been made aware of the vandalism and Liverpool City Council is working to get the repairs done quickly.
Sir Ken’s gravestone now had to be removed from its final resting place to be further cleaned, while Cilla’s gravestone could be repaired on site.
“We urge anyone with information about the person(s) responsible to contact the police”.
He was buried together with his mother Sarah and father Arthur in a private funeral at Allerton Cemetery in Liverpool.
Sir Ken died on 18 March 2018 at the age of 90 in his home in Knotty Ash, the same house where he was born and raised.
Surprise! Surprise! Star Cilla Black was buried just a few feet from her parents’ grave and her tombstone is a marble monument that she describes as a “devoted mother and grandmother”.
Cilla died in August 2016 at the age of 72, and her tombstone bears her name “Cilla Black OBE” above the single word “singer”.
It reads: “Singer”: “Beloved wife of Bobby, devoted mother and grandmother”. She celebrated life to live it and loved to entertain”.
On the gravestone is also her full name, Priscilla Maria Veronica Willis, née White, and her dates of birth and death: May 27, 1943 and August 1, 2015.
Cilla died in August in her villa in Spain from a stroke after she lost her balance while sunbathing and fell.
Her funeral took place at St. Mary’s Church in Woolton – where she married her late husband Bobby Willis in 1969.
The gravestone also contains lyrics from some of Cilla’s most famous songs, Step Inside Love, Alfie and You’re My World.