[p1necone]

Chartreuse doesn't really have any good substitutes that I can think of, it's got a very distinct flavour that's nothing like absinthe (I like to lovingly describe it as lawn steeped in everclear).

Still make the drink with absinthe and see how it goes though - it'll taste totally different but it might still be good, and the ABV and (lack of) sweetness of chartreuse and absinthe are at least fairly close.

[mkozlows]

Genepy is the best substitute. But now that the monks aren't making as much, other subs have popped up.

But definitely not absinthe.

[voxadam]

In my opinion, Genepy is a decent substitute for Yellow Chartreuse, not so much for Green. Green has a very herbal flavor where yellow tends to be more floral.