Getting from Marco Polo airport to Venice

The last No 5 bus is about 40 past midnight. I guess the question is; where are you going? You can get a land taxi to Piazzzle Roma and "N" boat runs all night down the Grand Canal. You can also arrange a water taxi in advance to pick you up at the airport. That will run you about 120 EUR. And staying at one of the many airport hotels for the night can be a good option.

I would stay at an airport hotel and start fresh in the morning. Have a change of clothes and other nighttime necessities in your personal item and you won't even have to unpack.

That late arrival precludes the bus, and a vaparato, not to mention the hotel check in at that late time. Be cautious about private water taxis as they are very expensive. Very!

Last month in Venice, a tour guide told me there's a fixed fee for the water taxi from the airport to Venice - €150. There may be an additional surcharge for late-night travel. Take the bus or a land taxi to the bus station (Piazzele Roma) as Sam says. Be sure you have exact directions to your hotel from there.

A prebooked water taxi for pick up after 10 pm is 120 EUR for the airport to any Venice hotel.
https://www.motoscafivenezia.it/eng/
And vaporettos really do run all night on the night boat schedule. But if you show up very late, you might find your hotel door locked unless it is a higher end place with 24 hr front desk.

I agree to stay near the airport. You can then take the bus into the Mestre and then take a train or bus into Venice in the morning (if cost is a concern). Mainly, this would allow you to rest before Venice which can be hectic.