Princess Alexandrine of Baden (Alexandrine Luise Amalie Friederike Elisabeth Sophie; 6 December 1820 – 20 December 1904) was the Duchess of Saxe-Coburg and Gotha as the wife of Ernest II. She was born the eldest child of Leopold, Grand Duke of Baden and his wife Princess Sophie of Sweden.

Before he ascended the throne, Alexander II of Russia was sent to Baden in order to present himself as a suitor for Alexandrine's hand in marriage. Alexandrine already regarded herself as his betrothed, as all the preliminary negotiations had taken place. On the journey there however, Alexander visited the court of Hesse-Darmstadt and met Princess Marie of Hesse and eventually married her.

At the urging of his brother Prince Albert, The Hereditary Prince Ernst of Saxe-Coburg and Gotha (born 1818) began to search for a suitable bride. Albert believed that a wife would be good for his brother; "Chains you will have to bear in any case, and it will certainly be good for you... The heavier and tighter they are, the better for you. A married couple must be chained to one another, be inseparable, and they must live only for one another". With this advice in mind (though Albert was reprimanded for presuming to counsel his elders), Ernest began searching.

Around this time, Ernest was suffering from a venereal disease brought on by his many affairs; Albert consequently counseled him from marrying until he was fully recovered. He also warned that continued promiscuity could leave Ernest unable to father children. Ernest waited a few years before marrying as a result.

On 13 May 1842 in Karlsruhe Ernest married Princess Alexandrine. To the consternation of his brother and sister-in-law Queen Victoria, the marriage failed to "settle down" Ernest. Alexandrine accepted all his faults cheerfully enough however, and began a fierce devotion to Ernest that would become more and more baffling to the outside world.

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