The Bones Family
"Edgar Bones ... he was a great wizard..."
-- Alastor Moody (GF)
Edgar was a member of the Order of the Phoenix in the 1970s; Moody said "he was a great wizard." Killed, with his wife and children, by a Death Eater before Voldemort fell (OP9). Brother of Amelia Susan Bones, uncle of Susan Bones.
In the film version of Order of the Phoenix , Edgar Bones was played (in the Wizard photograph of the Order) by First Assistant Director Cliff Lanning. 
Mr. and Mrs. Bones
Killed by Death Eaters in the 1970s (PS4, BN). Either Susan's grandparents or her aunt and uncle Edgar. When asked in a 2000 interview if the Boneses who were killed were related to Susan, JKR said "They were her grandparents." Rowling may have later changed the relationship when she wrote book five.
Amelia Susan Bones (d. 1996)
Sister of Edgar bones, and the aunt of Susan Bones. Before her murder by Death Eaters, Amelia was the Head of the Department of Magical Law Enforcement (OP6) and presided over the Wizengamot (OP8), including Harry's disciplinary hearing on August 12, 1995. She later told her niece Susan some of the details. Described as having a broad, square-jawed witch with very short gray hair, thick eyebrows and a monocle. According to Tonks, Amelia was fair and honest. Murdered "nastily" by Death Eaters in the first weeks of the Second Wizarding War (late June or early July 1996) (HBP1). Muggle newspapers reported the crime and described her as a "middle-aged woman who lived alone." Fudge believes that the murder was carried out by Voldemort himself (HBP1).
Susan Bones (b. circa 1980)
Student at Hogwarts, 1991-1998 (PS7); sorted into Hufflepuff.
Susan wears her hair in a long plait down her back. In October 1995 became a member of Dumbledore's Army (OP16). She acquired a gruesome notoriety when the Death Eater who killed her uncle Edgar and his family escaped Azkaban in January 1996. After the escape Susan told Harry that she now knew what he'd had to go through with everyone staring and talking about him (OP25). Susan was one of the Dumbledore's Army members who helped Harry cope with Malfoy in the ambush on the Hogwarts Express (OP38).
In 2001 Rowling flashed a notebook during a BBC interview that showed her notes on the students in Harry Potter's year and Susan is noted as being a Half-blood in Hufflepuff House. This information cannot be considered canon, however, because the notes conflict in too many places with the stories as they were actually published.
Susan is most likely named after her Aunt Amelia, whose middle name is Susan (OP8).