I dug around a little (no pun intended) and found mention of more than the ghosts of the Lincoln family haunting the white house. Many more, as a matter of fact.
At the North Portico (the front entrance), Anne Surratt's ghost has been seen hammering at the doors, begging for her mother to be released. Mary Surratt was accused of participating in a conspiracy to assassinate Abraham Lincoln in the hysterical aftermath of the first presidential assassination. She was convicted, and executed in 1865. Every July 7, the anniversary of Mary's hanging, marks another appearance by Anne's ghost. Mary lived in an apartment building on H Street; for years after her death, subsequent tenants reported hearing moaning and sobs.
An unfriendly ghost, that of a British soldier who is said to be one of the members of Britain's attempt, in 1814, to burn the White House, is said to walk in front of the house at night. He always has a flaming torch in one hand.
Dorothea Paine ("Dolley") Madison, wife of President James Madison, appeared in a fit of pique in the Rose Garden when Woodrow Wilson was President. The garden was established by Dolley a hundred years before, but Wilson's wife Ellen wanted to have it dug up. Workmen claimed that the ghost of Dolley Madison appeared and prevented them from doing the work. No one else has ever tried to change, much less eliminate, the garden.
Reports state that William Henry Harrison's ghost can be heard digging around in the attic - though how anyone knows it's the ghost of Harrison simply by hearing him, is unexplained.
A Demon Cat is said to haunt the basement - or the basement of the U.S. Capitol Building, depending on which version you read. When the cat appears, a major disaster is likely to occur soon. A White House guard claimed he saw it a week before the 1929 stock market crash; it was also seen just before the assassination of JFK.
Abigail Adams (wife of John Adams) has been seen hanging laundry in the East Room. When she lived in White House, this was the best room for this purpose. Even now, she can be seen hurrying towards the East Room, holding her arms out as if she is carrying laundry. The East Room is also the room in which Abraham Lincoln's body lay in state.
Winston Churchill refused to sleep in Lincoln's former bedroom after seeing the ghost of Lincoln himself. One embarrassing night, Churchill (still staying in the Lincoln Room) took a long bath, drinking a glass Scotch and smoking one of his trademark cigars. Still smoking, he got out of the bath and went into the bedroom, naked. He saw Lincoln standing by the fireplace and leaning on the mantle. They looked at one another for a long moment while the apparition slowly disappeared. (It seems that the fireplace held some sort of significance for Lincoln; Maureen Reagan and her husband, Dennis, saw his translucent figure next to it.)
Andrew Jackson is said to haunt his old canopy bed in the Rose Room. A strange cold spot and the sound of laughter issuing from the bed have been reported. His ghost laughs, swears, and yells.
Harry Truman once wrote in a letter to his wife: "At 4 o'clock I was awakened by three distinct knocks on my bedroom door. No one there. Damned place is haunted, sure as shootin'!"