| Prince Frederick William | |
| House: | House of Solms-Braunfels |
| Father: | Ferdinand William Ernest, Prince of Solms-Braunfels |
| Mother: | Countess Sophie Christine Wilhelmine of Solms-Laubach |
| Spouse: | Frederica of Mecklenburg-Strelitz |
| Issue: |
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| Birth Date: | 22 October 1770 |
| Birth Place: | Braunfels |
| Death Place: | Sławięcice |
Prince Frederick William of Solms-Braunfels (22 October 1770 in Braunfels – 13 April 1814 in Slawentzitz) was a Prussian Major General and by birth member of the House of Solms-Braunfels.
He was the fourth son of Ferdinand William Ernest, 2nd Prince of Solms-Braunfels (1721–1783) and his wife, Countess Sophie Christine Wilhelmine of Solms-Laubach (1741–1772).
He became known mainly through his marriage to Princess Frederica of Mecklenburg-Strelitz. She was the widow of Prince Louis Charles of Prussia (1773–1796). When she became pregnant in 1798, he married her in order to avoid a scandal. The daughter died soon after birth. Frederick William was alleged to have been strongly inclined to consume alcohol and had to quit military service in 1805 for health reasons. He also lost his income and even his brother advised Frederica to divorce. She was initially against it, but when in 1813, she met Ernest Augustus, King of Hanover (1771–1851), she, too, wanted the divorce. Before they got around to it, however, Frederick William died, in 1814 in Sławięcice.
From his marriage to Duchess Frederica of Mecklenburg-Strelitz, the following children are known: