In brightest day, in blackest night,

No evil shall escape my sight

Let those who worship evil's might,

Beware my power... Green Lantern's light! -Green Lantern Oath

In blackest day, in brightest night,

Beware your fears made into light

Let those who try to stop what's right,

Burn like his power, Sinestro's might! -Sinestro Corps Oath

In fearful day, in raging night,
With strong hearts full, our souls ignite,
When all seems lost in the War of Light,
Look to the stars-- For hope burns bright! -Blue Lantern Corps Oath

With blood and rage of crimson red,

Ripped from a corpse so freshly dead,

Together with our hellish hate,

We'll burn you all--That is your fate! -Red Lantern Corps Oath

Tor lorek san, bor nakka mur,

Natromo faan tornek wot ur,

Ter lantern ker lo Abin Sur,

Taan lek lek nok -- Formoorow Sur! -Indigo Tribe Oath

For hearts long lost and full of fright,

For those alone in blackest night,

Accept our ring and join our fight,

Love conquers all-- With violet light! -Star Sapphires Oath

The Blackest Night falls from the skies,

The darkness grows as all light dies,

We crave your hearts and your demise,

By my black hand--The dead shall rise! -Black Lantern Corps Oath

Larfleeze doesn't really have one, but I think this would suit Agent Orange perfectly:
 

Mine mine mine, mine mine mine mine,

Mine mine mine mine mine mine mine

Mine mine mine mine mine mine mine mine,

Mine mine mi- ooh, shiny!