Célèbre vs. fameux vs. connu
The French language has a rich vocabulary for describing fame and celebrity. 'Célèbre', 'fameux' and 'connu' all belong to the realm of fame, but with nuances that distinguish them in usage.
Célèbre
Used to denote someone or something that is widely acclaimed and recognized, often for positive accomplishments or qualities.
Marie Curie est une scientifique célèbre.
(Marie Curie is a famous scientist.)
La Joconde est un tableau célèbre du Louvre.
(The Mona Lisa is a famous painting at the Louvre.)
Fameux
Can imply fame, but often carries a connotation of infamy or notoriety; it can also suggest something is remarkable or excellent, sometimes ironically.
Le fameux bandit a échappé à la police encore une fois.
(The notorious bandit has escaped the police once again.)
Ce restaurant est connu pour son fameux coq au vin.
(This restaurant is known for its famous coq au vin.)
Connu
Refers to being known or recognized but does not necessarily carry the additional implication of prestige or esteem that 'célèbre' might.
Cet acteur est bien connu en France.
(This actor is well-known in France.)
"Les Misérables" est un roman connu de Victor Hugo.
('Les Misérables' is a well-known novel by Victor Hugo.)
Summary
While 'célèbre' denotes wide acclaim, often for positive reasons, 'fameux' leans towards notoriety or excellence with an occasional ironic twist, and 'connu' simply indicates recognition without implied esteem. The subtle differences in these words allow French speakers to express various levels and types of fame with precision.