This article deals with the Roman consul who was co-consul and co-censor with Cato the Elder. For other men with this name, see Lucius Valerius Flaccus (disambiguation).

L. Valerius Flaccus (or Lucius Valerius P.f. Flaccus, who died 180 BC), was consul in 195 BC and censor 183 BC, both times with his great friend Cato the Elder, whom he brought to the notice of the Roman political elite. Flaccus, a patrician and son of the consul Publius Valerius Flaccus (consul in 227 BC), became friend, political patron and ally of the young plebeian soldier Marcus Porcus Cato, later called Cato the Elder, during the earlier years of the Second Punic War. The two men shared common conservative political sympathies and cultural outlook. Both were loyal to the military and political views of the older generation represented by Quintus Fabius Maximus.

Flaccus was curule aedile in 201 BC, praetor in Sicily in 199, and finally consul with Cato in 195. Flaccus defeated the Boii and Insubrians during his consulship, then in 191 was legate at Thermopylae. As triumvir in 190, he helped defend Placentia and Cremona and founded Bononia (modern Bologna).

He was elected censor along with Cato in 184 and princeps senatus when Scipio Africanus Major died. Flaccus died in 180. Politically, Flaccus was a conservative and joined Cato in the role of defending Roman tradition against Hellenism.

His brother was the flamen dialis Gaius Valerius Flaccus, who made a respectable political career as praetor, though not consul. Both men were apparently sons of the consul Publius Valerius L.f. Flaccus; the father had been elected consul for 227 BC with Marcus Atilius M.f. Regulus.

ca:Luci Valeri Flac (cònsol 195 aC) de:Lucius Valerius Flaccus (Konsul 195 v. Chr.) es:Lucio Valerio Flaco (siglo II a. C.) fr:Lucius Valerius Flaccus (consul en -195) la:Lucius Valerius Flaccus nl:Lucius Valerius Flaccus (consul in 195 v. Chr.)