Isabelle of Luxembourg

Isabelle of Luxembourg (c. 1247–1298) was the daughter of Henry V of Luxembourg and Margaret of Bar. In 1265 she married Guy of Dampierre, Count of Flanders, as his second wife, settling her family's dispute with Guy over Namur. Her children included John I, Marquis of Namur, and a daughter Philippa.

Guy's plan to wed Philippa to Edward, Prince of Wales was crushed by Philip IV of France, who imprisoned her in Paris. Isabelle died in September 1298; Philippa remained captive until her own death in 1306.