Biography
The ladykiller, the player, the rake — a man who relentlessly pursues, lands, loves, and then abandons members of the opposite sex, a skill bestowed upon him to demonstrate just how attractive he is. Sometimes comic, sometimes sinister, always successful, this character leaves behind a string of broken hearts, and occasional vows of revenge that are rarely fulfilled. The Casanova's only motivation is indulging his lust and desire, sating them with the bodies of his completely willing conquests.
Contrast with the unsuccessful Casanova Wannabe. Compare with the inexplicable Kavorka Man. A guy who gets the girls like a Casanova, albeit unintentionally, is a Chick Magnet. If kind-hearted, may overlap with Chivalrous Pervert. The Charmer is equally charming but less sex-obsessed. If they really get around but want to settle down, it's Looking for Love in All the Wrong Places. A Handsome Lech has more negative connotations and a sparser scorecard than the Casanova.
The trope is named for Giacomo Casanova (1725-1798), an Italian soldier, spy, diplomat, adventurer, and librarian whose extensive but unreliable autobiography (in which he almost literally described himself as God's Gift to Womennote ) established his eternal fame as a lover. It should be noted that the historical Casanova was closer to a Chivalrous Pervert who really was looking for love... just with women who were locked in loveless political marriages — and also achieved his successes despite being famously ugly. (Definitely◊ he was no Heath Ledger.◊) Interestingly, he was one of the few 18th-century men who bathed almost daily and asked the same thing from his partners (this may have aided him in his sex appeal, if most other guys stank to high heaven).
For the juvenile version — all of the above without the sex — see KidAnova. Contrast the Serial Romeo (who falls in love with a long succession of women, one at a time and for reasonable periods). If the guy is actually only rumored to be a Casanova and has no evidence onscreen, it's the Urban Legend Love Life. If a guy continues acting like this even if he's in a committed relationship he's also a Serial Adulterer (unless he's in an open relationship). If he develops feelings for one of his conquests (or someone who refuses him), he's a Ladykiller in Love. If that love transforms him into a committed and responsible partner and father, then he's become a Reformed Rake. See More Friends, More Benefits for when the mechanics of a game encourage the player character to act this way. If he's malicious, he may be an Intentional Heartbreaker.
Note: It should be mentioned that even after the affairs were over, most of Casanova's ex-lovers still liked him, and he was reputedly quite the gentleman. This trope would probably fit (the fictional) Don Juan better.
Finally, a warning: Despite Maneater being a redirect, this trope should NOT be confused with I'm a Humanitarian or the Literal Maneater.
See also Spies Are Lecherous. See Horny Bard for the fantasy, more musically inclined equivalent.