Sikelgaita, duchess of Apulia (born c. 1040)

Sikelgaita was a Lombard princess, the daughter of Prince Guaimar IV of Salerno and second wife of Duke Robert Guiscard of Apulia. Her heritage made her a vital asset to Robert's governance in Southern Italy, legitimizing his reign and that of his successors. Sikelgaita frequently accompanied Robert on campaigns and is noted for leading troops in battle. She continued to be a significant source of support for her primary heir, Roger Borsa, and remained actively involved in politics until her death.

Year 1040 (MXL) was a leap year starting on Tuesday of the Julian calendar.