Mega Fatty

Mega Fatty is a boss that appears in The Caves. He appears as a huge version of a Fatty.

Behavior

Mega Fatty has 5 attacks in total:

He will perform a short-range, very quick jump to the player's position, leaving Red Creep when he lands.
He will perform a long-range, longer jump, also leaving Red Creep when he lands, assuming the player is not in range for the short jump.
He will inhale and draw the player, objects, and any monsters towards him, and then vomit upwards, unleashing a barrage of projectiles in the player's direction. The vomit itself is harmless, but the projectiles it produces will seek until they land, rather than until he stops spawning them, so keep moving!.
He will occasionally fart, which can damage Isaac if he's too close, summoning 1-2 Dips.
He will occasionally poop, unleashing a barrage of projectiles behind him.

Red: Smaller and has 10% less health. Shoots 6 bullets instead of leaving Red Creep upon landing. Poops Red Poop instead of Dips. Vomit attack moves outward in a pattern similar to Mom's Heart/It Lives's four slower bullet stream attacks.
Brown: Has 15% more health. Never uses his vomit attack and sends out lines of rock waves instead of leaving Red Creep upon landing when performing the long-range jump, similar to The Cage.

When Mega Fatty is shooting out his barrage of projectiles, it is very easy to see the shadows of the projectiles, allowing you to determine when it is safe to stop moving.
The Lost Contact will still block all incoming projectiles from his barrage even if they happen to go high enough to be offscreen.

The Cage is the posthumous version of Mega Fatty.
Mega Fatty has the highest health of any boss fought in Chapter 2.
The picture of Mega Fatty on Isaac's last will closely resembles the unused variant.