Her appearance is similar to a Trite, which is a light tan-colored, four-eyed spider with an upside down face, 4 eyes (two larger while others smaller), and crooked-looking teeth. She sports with 4, bony legs each ended with a toe for feet.
Widow jumps around the room to deal contact damage, similar to Monstro (unlike Monstro, however, she can jump almost twice as far and takes longer to rest before jumping again).
Widow occasionally spits out Spiders. She can also leave a puddle of white Creep on the ground which will slow Isaac's movement, but not damage him. She will often spawn Sacks in those puddles.
Widow can only have a maximum of two Sacks around at any given time, so it may prove beneficial to leave the Sacks alive if the player believes they can take out Widow fast enough.
If the Sacks and the Spiders are swarming Isaac and give problems, it could be useful to "bait" Widow's jumps directly on them, since she'll destroy every spawned unit she jumps onto.
The white fluid Widow releases when spawning Sacks does not damage the player, but slows movement considerably. It is important to keep this in mind as Widow can easily close the distance when the player is stuck on it.
Widow has a low amount of health, similar to the Duke of Flies. Therefore, Bombs can prove to be very effective against her.
Smaller size but jumps twice as fast. Regurgitates Attack Flies and spawns Boils and Guts. Jumps at lower distances, but much faster.
Shoots projectiles similar to Loki or Peep and spawns B. Spiders as opposed to regular ones. Also leaves a black creep similar to Gish that has the same effect as the white creep used by the normal Widow variant.
Rapidly jumps multiple times, usually 3-4 times, each jump shoots 4 projectiles from where Widow lands in an X shaped pattern. Spawns Sacks and coughs up spiders.
Widow can damage other Widows when encountered as a miniboss by jumping over them.
Widow could be considered an upgraded version of Trite, both sharing the same "aimed jumping" tactic along with the upside-down face.
This boss may be a reference to one of the forms the creature takes in John Carpenter's movie "The Thing".
Alternatively, the Widow bears a strong resemblance to the spiders in the FPS video game Doom 3, which have a similar upside down face.