The Sirian Werebull is a strange hybrid that was created by crossbreeding Sirian DNA with an unknown species of cattle. They have two hands on their front legs, and hooves on their back legs. Unlike normal cattle, Werebulls have sharp teeth similar to that of a carnivore.
Behavior-wise, the Werebull behaves just like an ordinary bull. They are very aggressive and dangerous, and will begin charging towards the target as soon as they see them. They will not stop chasing their prey until the Werebull or the target has been killed or if the Werebull loses sight of them. A Werebull will even charge through Mental-affiliated units and ram them out of the way, just to get to the player. Its horns are its only defense, but this does not mean that the Werebull is an easy opponent; the horns are razor-sharp and the animal can build up considerable speed during its characteristic attack charges.
In-game, the Werebull has medium health and is one of the fastest enemies, making them a dangerous foe. The Werebull's health allows it to endure several hits from most weapons before dying. Its two attacks that consist of ramming the player, which causes the player to go flying into the air, or if the player is not fast enough, it will attempt to gore the player with its horns, causing the same damage as a ram would. The Werebull is capable of throwing the player over walls using its horns. Occasionally, the player may end up getting stuck in an inaccessible part of the map, which can sometimes result in having to reload to the last save point. Worse, a Werebull can send a player falling to their death.
In The Second Encounter in The City of the Gods, there are several Werebulls armed with cannons that will fire a volley of fast cannonballs at the player. These cannonballs are very hard to dodge and deal massive damage, if not kill and gib the player outright, although there is a chance that these Werebulls may kill themselves instead, particularly if the player lures one towards them and against a wall. This is the only level where they use cannons.
In Serious Sam 4, the Werebull can be ridden by the player if they have unlocked the respective skill in the S.A.M. system. When riding a Werebull, the same controls for riding a vehicle apply to the Werebull. The player can also fire their weapons from the Werebull while riding it. Like other mountable enemies, the Werebull's health will be displayed by a HUD icon on the bottom-left corner of the screen. Once the Werebull is dead, the player will be dismounted from it.
By far, the most important thing a player can do against Werebulls is to keep moving and strafing. Continuously moving prevents the Werebull from catching up to the player, and strafing prevents it from being able to hit the player.
When paired with other enemies, the Werebull is a high-priority target. Their charge attacks are powerful. And trying to dodge them while dealing other enemies is difficult.
Charged up SBC Cannon cannonballs are very effective against groups of Werebulls. A charged up ball can tear through an entire group with ease (compared to the one or two a non-charged cannonball can kill).
Serious Sam 1
One or two Werebulls can be taken out with the Double Barrel Coach Gun. However, this should only be done if there are weak or easy to avoid enemies near the Werebull, as it takes time to kill the Werebulls because of the long reload time between coach gun shots.
If the player doesn't have a cannon and needs to kill a group of Werebulls, the XM214-A Minigun and the XL2 Lasergun can inflict a significant amount of damage on groups as well.
The XOP Flamethrower can also do major damage to a pack of Werebulls, but several seconds of continuous fire is needed to kill one.
At close range, explosive weapons are not recommended against Werebulls because there is a very real possibility of one getting close to the player while the explosive is in the air, causing the player to be harmed by the explosive's splash damage. At long range, it's a good option. Getting hit by a grenade makes a Werebull do a jump, though, so it's a bit harder to land a second shot.
A zoomed in RAPTOR Sniper Rifle shot will always kill a Werebull in one hit, which is useful for taking them out before they can even get close to the player.
In more confined areas, Werebulls are much more dangerous as they can turn around much faster. Aside from the charging attack, they can also stab the player with horns in these situations. The horn stab is not as damaging, but is much more difficult to avoid.
The more direct hits the player takes, the greater damage they receive. Jumping while dodging increases the chance of much smaller damage when getting hit, although the knockback is still retained. This is also true for Cucurbito the Pumpkin.
In The City of the Gods, the cannon-armed Werebulls are high-priority targets and must be killed with the cannon, MK III Grenade Launcher, or sniper rifle immediately once spotted because their cannonballs are difficult to dodge and can instantly gib the player if not killed soon enough.
Serious Sam Advance
The Werebull's attack can be dodged by strafing to the left or right while it's charging. This will make the Werebull miss, giving the player a few seconds to attack it while it's trying to readjust itself to charge again.
The coach gun and Thompson submachine gun are effective against the Sirian Werebull. The Thompson can quickly do a good amount of damage on it per hit thanks to the amount of damage it does per bullet and its rate of fire. Its bullets can also briefly stun the Werebull, giving the player more of a change to dodge the Werebull. The coach gun is surprisingly not as effective as the Thompson because of its slow rate of fire and damage per second, but it works in a pinch.
The rocket launcher is effective against the Sirian Werebull, but it can be dangerous for the player if they are facing the Werebulls in a small arena. The Werebull can quickly close the distance between the player and itself while the rocket is in-air, which may cause it to explode close to the player, harming them.
Groups of Werebulls should be dealt with by using either the minigun or the rocket launcher. The Minigun's high rate of fire and lack of potential self-damage make it easy to kill Werebulls before they get too close, while the rocket launcher can kill multiple Werebulls with a few rockets, especially if they're close together.
When paired with other enemies, the Werebull is a high priority target. Trying to dodge them while dodging other enemy attacks can be difficult and cause the player a lot of grief. Eliminating them ASAP makes it much easier to dodge other enemy attacks.
Groups of Werebulls can be taken out with the XM4000 Minigun and Sirian Power Gun. Their high rate of fire can take down Werebulls in no time. The double-barrel shotgun is also a good choice if the player is good at dodging them, as it is a one-hit kill and has a somewhat-low reload speed.
Werebulls should be a high-priority target because of how damaging they are and how it can be easy to lose track of them in a large firefight.
Serious Sam 3: BFE
Like its classic counterpart, the Sirian Werebull's charge can be avoided by strafing in one direction. Strafing at an angle makes it easier to avoid its charge, so try that whenever it's possible.
The coach gun works great against the Sirian Werebull; two shots with it can kill a Werebull if most of the pellets hit. Alternatively, the Sledgehammer can kill them with a few hits. A sideways attack hits them more reliably than the downwards attack.
The best chance to shoot it with the coach gun is when it's close while dodging. It may take some practice, but the player can easily shoot the Werebull with every pellet connecting.
Using the Sirian Mutilator against a Werebull will lasso onto it and eventually decapitate it, though this can be rather risky, as this usually requires the player to directly face the Werebull. An experienced player can take out several Werebulls with the Mutilator at once with enough timing and safe distance.
Multiple Werebulls should be taken out with heavy-duty weapons, such as the A-24 Devastator, C-4 Demolition Charges or the SBC Cannon. One charge can wipe out a Werebull in one hit and greatly damage the other it if one of them walks over it when it blows up, or it's attached to the Werebull, while one cannonball can kill multiple Werebulls, even if it isn't charged up.
When paired with other enemies, the Sirian Werebull is a medium-high-priority threat. Its attacks are powerful, and trying to dodge it while dealing with other enemies is difficult. Killing it ASAP makes it easier for the player to avoid other enemies and their projectiles. However, some other targets firing hitscan projectiles should be dealt with before Werebulls.
Taking a direct hit by a Werebull charge can send the player to high places, such as a ledge or roof that would otherwise be impossible or very difficult to jump or climb onto. This can be exploited to access otherwise impossible-to-reach secrets.
Serious Sam's Bogus Detour
Sirian Werebulls are extremely fast and dangerous. The player should dash or strafe sideways as soon as they hear or see one.
The cannon, lasergun, minigun and Devastator are effective weapons against the Werebull.
Avoid their charge attack whenever possible, as it deals a lot of damage.
Serious Sam 4
The Werebull can be instantly killed with the coach gun up close if the player shoots it in the head and all of the pellets connect.
For groups of Werebulls, dual-wield coach guns or the Autoshotgun are very useful on them.
The Devastator, grenade launcher and RAPTOR also work well on Werebulls, and are an instant one-shot kill if they are shot in the head.
If the player has the appropriate S.A.M. skills, they can mount a Werebull and use it to ram into other enemies until its health runs out.
When riding a Werebull, the Werebull's high speed makes it harder for other enemies to hit it. This can be useful for running away from large swarms of fast but weaker enemies like Gnaars or Processed Anthropolyps or for evading enemy projectiles. However, it is recommended that the player ride a fully healthy Werebull to be able to ride it for as long as they need to.
The Werebull's speed also comes in handy for the "Armed, Farmed, and Alarmed" sidequest in One for the Road, as it can help the player get to the FRPCL's location quickly and return back to the main path just as quickly as well.
Behind the scenes
An early Werebull model can be seen in the Serious Sam announcement movie. It had a less detailed skin and much longer horns.
They were two variations of the Werebull skins: the summer and the winter skin, as seen in SDK 1.07. Unfortunately, it may of been scrapped from the game.