A different take on the old Basilisk, using the Medieval Bestiary as a source.
According to the Bestiary:
The basilisk is usually described as a crested snake, and sometimes as a cockerel with a snake’s tail. It is called the king (regulus) of the serpents because its Greek name basiliscus means “little king”; its odor is said to kill snakes. Fire coming from the basilisk’s mouth kills birds, and its glance will kill a man. It can kill by hissing, which is why it is also called the sibilus. Like the scorpion it likes dry places; its bite causes the victim to become hydrophobic. A basilisk is hatched from a cock’s egg, a rare occurence. Only the weasel can kill a basilisk.
This fearsome beast is the size of an overly large cockerel, about the size of a small dog. Giant weasels are its natural enemy, being immune to its gaze, smell and hissing. A weasel’s scent is poisonous to the basilisk and if within ten feet the beast will always attempt to flee; if within five feet or less it must make a saving throw versus poison or suffer 1d4 damage per round.
# Encountered: 1
Movement: 60′ (180′)
Hit Dice: 3
Armour Class: as chain
# Attacks: 1 bite plus special
Damage: 1d4 or special
Save as: F3
A basilisk emits a foul, bitter smell that kills any snakes (or related creatures) of 1 HD or less; others suffer 1d4 damage per round if within ten feet. It can breath fire every other round, which deals 1d4 damage to anyone caught in its 10′ cone of flames (save versus breath weapon for half): it can also spit this fire, but reserves this for birds, which it then eats.
The glance of a basilisk can kill any human, demi-human, humanoid or monster of less than its own Hit Dice; this has a range of 30 feet and a saving throw versus paralysis is allowed: success means crippling pain that renders the victim inactive for 1d4 rounds; failure results in death. A mirror can be used to reflect the basilisk’s gaze back onto itself, which has the same chance of killing it. Higher Hit Dice creatures suffer crippling pain on a failed save, or moderate pain on a success (equal to 1d6 damage).
The basilisk can also hiss: this makes ears bleed, curdles the brain, and can be deadly. It can hiss every 1d6 rounds, effective up to 60 feet. A saving throw versus poison negates the effect, otherwise the victims suffer 1d8 damage per round. The basilisk can sustain its hissing for a number of rounds equal to its Hit Dice, but can take no other action except moving.
Finally, the bite of the basilisk may infect the victim with a disease: Fear of Water. A save versus poison resists, otherwise incubation is 1d4 days and the victim will steer clear of water, possibly suffering from dehydration, until cured (by magic, Cure Disease, or bed rest and a new save every three days).
And now an encounter location for said beast:
Lair of the Basilisk
This cave lies hidden in a dry gully of a forested hill. The entrance is only a few feet high, and anyone of medium size or larger has to crouch down to gain entry.
The back of the cave is partially hidden by rocks placed there by the basilisk, concealing its lair. Beyond is a small pool of water, fed by an underground stream, and a nest of bones, branches, and assorted junk found in the forest.
Lying on the nest is the basilisk, sleeping at night. It defends its lair ferociously. There is a 1 in 6 chance that it has 1d4 eggs waiting to hatch into baby basilisks (5% chance of them hatching into a cockatrice instead).