Valeria Messalina was the third wife of the emperor Claudius. In Claudius' absence she married Caius Silius and attempted to place him on the throne. She was killed when the plot failed.

Valeria Messalina, AD c.22-48, married Claudius, later Roman Emperor Claudius I, in 39 or 40. She bore him two children, Britannicus and Octavia. Extremely promiscuous, Messalina manipulated her husband into executing a number of those who rejected her advances or otherwise angered her, but she herself was executed after Claudius's secretary Narcissus informed the emperor of her secret marriage to Gaius Silius.

According to the De Imperatoribus Romanis article on Claudius,

In 38 A.D. Claudius had married Valeria Messalina, a scion of a noble house with impressive familial connections. Messalina bore him a daughter (Octavia, born in 39) and a son (Britannicus, born in 41): she was therefore the mother of the heir-apparent and enjoyed influence for that reason. In the sources, Messalina is portrayed as little more than a pouting adolescent nymphomaniac who holds wild parties and arranges the deaths of former lovers or those who scorn her advances; and all this while her cuckolded husband blunders on in blissful ignorance. Recently, attempts have been made to rehabilitate Messalina as an astute player of court politics who used sex as a weapon, but in the end we have little way of knowing the truth.[[19]] What we can say is that either her love of parties (on the adolescent model) or her byzantine scheming (on the able courtier model) brought her down. While Claudius was away in Ostia in AD 48, Messalina had a party in the palace in the course of which a marriage ceremony was performed (or playacted) between herself and a consul-designate, C. Silius. Whatever the intentions behind it, the political ramifications of this folly were sufficiently grave to cause the summary execution of Messalina, Silius, and assorted hangers-on (orchestrated, tellingly, by the freedman Narcissus).[[20]] Claudius was now without a wife.

[[19]] Messalina was Claudius's third wife: previous unions with Plautia Urgulanilla and Aelia Paetina had failed for various reasons; see Suet. Claud. 26.1-2. Messalina's influence is indicated by her appearance on the obverse of coins of Claudius's reign (where one would expect the head of the emperor), or in the cameo now in Paris depicting Messalina, Octavia, and Britannicus. Messalina's excesses are reflected in such sources as Sen. Apoc., passim and Juv. Sat. 6 and 10.

[[20]] Messalina's fall: Tac. Ann. 11.26-37; Suet. Claud. 26; Dio 60(61).31.1-5; Sen. Oct. 257-61.

See also the Geocities Tempus site on Messalina