thumb|125px|Coat of arms of the Dukes of Aosta
Duke of Aosta (; ) was a title in the Italian nobility. It was established in the 13th century when Frederick II, Holy Roman Emperor, made the County of Aosta a duchy. The region was part of the Savoyard state and the title was granted to various princes of the House of Savoy, second sons of the reigning king of Sardinia or king of Italy.
The title was re-created in 1845 for Prince Amadeo, son of Victor Emmanuel II, and thereafter held by him and his descendants until the abolition of the Italian monarchy in 1946. Two holders briefly served as kings of European countries – Prince Amadeo ruled as king of Spain from 1870 to 1873, while his grandson Prince Aimone was titular king of Croatia from 1941 to 1943 during the Italian-backed fascist regime.
The subsidiary titles of the Duke of Aosta were Prince della Cisterna and of Belriguardo, Marquess of Voghera, and Count of Ponderano, originating from the heritage of Maria Vittoria dal Pozzo, the mother of Duke Emanuele Filiberto. Ponderano was created in 1559, Voghera in 1618; Cisterna and Belriguardo as princely in 1670.
Duke of Aosta, 1701–1715
{| style="text-align:center; width:100%" class="wikitable"
! width=15% | Name !! width=9% | Portrait !! width=20% | Birth !! width=20% | Marriages !! width=20% | Death
|-
|width=auto| Charles Emmanuel III of Sardinia<br />1701–1715
| 100px|center
| 27 April 1701<br>Royal Palace of Turin<br>second son of Victor Amadeus II and Anne Marie d'Orléans
| (1) Anne Christine of the Palatinate-Sulzbach<br />15 March 1722 <br />Vercelli<br />one son<br />(2) Polyxena of Hesse-Rotenburg<br />20 August 1724<br />Toruń<br />six children<br />(3) Elisabeth Therese of Lorraine<br />1 April 1737<br />Royal Palace of Turin<br />three children
| 20 February 1773<br>Royal Palace of Turin<br>aged 71
|-
|}
Duke of Aosta, 1723–1725
{| style="text-align:center; width:100%" class="wikitable"
! width=15% | Name !! width=9% | Portrait !! width=20% | Birth !! width=20% | Marriages !! width=20% | Death
|-
|width=auto| Prince Vittorio Amedeo<br />1723–1725
| 100px|center
| 7 March 1723<br>Royal Palace of Turin<br>only son of Charles Emmanuel III and Anne Christine of the Palatinate-Sulzbach
| never married
| 11 August 1725<br>Royal Palace of Turin<br>aged 2
|-
|}
Duke of Aosta, 1731–1735
{| style="text-align:center; width:100%" class="wikitable"
! width=15% | Name !! width=9% | Portrait !! width=20% | Birth !! width=20% | Marriages !! width=20% | Death
|-
|width=auto| Prince Emanuele Filiberto<br />1731–1735
| 100px|center
| 17 May 1731<br>Royal Palace of Turin<br>second son of Charles Emmanuel III and Polyxena of Hesse-Rotenburg
| never married
| 23 April 1735<br>Royal Palace of Turin<br>aged 3
|-
|}
Duke of Aosta, 1738–1745
{| style="text-align:center; width:100%" class="wikitable"
! width=15% | Name !! width=9% | Portrait !! width=20% | Birth !! width=20% | Marriages !! width=20% | Death
|-
|width=auto| Prince Carlo Francesco<br />1738–1745
| 100px|center
| 1 December 1738<br>Royal Palace of Turin<br>eldest son of Charles Emmanuel III and Elisabeth Therese of Lorraine
| never married
| 25 March 1745<br>Royal Palace of Turin<br>aged 6
|-
|}
Duke of Aosta, 1759–1802
{| style="text-align:center; width:100%" class="wikitable"
! width=15% | Name !! width=9% | Portrait !! width=20% | Birth !! width=20% | Marriages !! width=20% | Death
|-
|width=auto| Victor Emmanuel I of Sardinia<br />1759–1802
| 100px|center
| 24 July 1759<br>Royal Palace of Turin<br>second son of Victor Amadeus III and Maria Antonia Ferdinanda of Spain
| Maria Theresa of Austria-Este<br />25 April 1789<br />Royal Palace of Turin<br />seven children
| 10 January 1824<br>Castle of Moncalieri<br>aged 64
|-
|}
Duke of Aosta, 1845–present
{| style="text-align:center; width:100%" class="wikitable"
! width=15% | Name !! width=9% | Portrait !! width=20% | Birth !! width=20% | Marriages !! width=20% | Death
|-
|width=auto| Amadeo I of Spain<br />1845–1890<br />(King of Spain<br/>1870–1873)
| 100px|center
| 30 May 1845<br>Royal Palace of Turin<br>second son of Victor Emmanuel II and Adelaide of Austria
| (1) Maria Vittoria dal Pozzo<br />30 May 1863<br />Royal Palace of Turin<br />three sons<br />(2) Maria Letizia Bonaparte<br />11 September 1888<br />Royal Palace of Turin<br />one son
| 18 January 1890<br>Royal Palace of Turin<br>aged 44
|-
|width=auto| Prince Emanuele Filiberto