| Frederick William | |
|---|---|
 | |
| Elector of Hesse | |
| Reign | 1847–1866 |
| Predecessor | William II |
| Successor | Electorate abolished |
| Born | 20 August 1802 Hanau, Holy Roman Empire |
| Died | 6 January 1875 (aged 72) Prague, Austria-Hungary |
| Spouse | Gertrude Falkenstein, Princess of Hanau |
| Issue | Princess Augusta of Hanau and Hořowitz Princess Alexandrine of Hanau and Hořowitz Prince Friedrich Wilhelm of Hanau and Hořowitz Prince Moritz of Hanau and Hořowitz Prince Wilhelm of Hanau and Hořowitz Princess Maria of Hanau and Hořowitz Prince Karl of Hanau and Hořowitz Prince Heinrich of Hanau and Hořowitz Prince Philipp of Hanau and Hořowitz |
| House | House of Hesse |
| Father | William II |
| Mother | Princess Augusta of Prussia |
Frederick William I (20 August 1802 – 6 January 1875) was, between 1847 and 1866, the last Prince-elector of Hesse-Kassel (or Hesse-Cassel).