Meek Mill -- My Party Lion Is Super Famous ... And Charges $3,000 Per Hour

File this Under: "Only In Hollywood" -- the caged lion at Meek Mill's humongous Grammy after-party moonlights as an actor ... and once starred in a movie with Matt Damon, TMZ has learned.

Sources connected to the lion tell us ... the lion's name is Felix -- and rapper Meek Mill shelled out $9,000 for the king of the jungle to appear at his Hollywood Hills mansion party for 3 hours.

As we previously reported, Mill's party was PACKED with huge stars like Diddy, Drake, Nicki Minaj and more ... but Felix happens to be a heavyweight in his own right.

We know ... Felix had a starring role in the 2011 flick, "We Bought a Zoo" ... which featured Matt Damon and Scarlett Johansson.

Felix has also starred in several commercials (he's not as proud about those -- but hey, he's gotta pay the bills).