There are some things in the Warhammer 40k universe that are indisputably iconic.
Think of the Space Marine, the Bolter, the Land Raider.
For Guard, think of the Lasgun, the Commissar, the Leman Russ.
One other icon I would make a case for would be the Basilisk. It has been around the 40k universe since pretty much the beginning of its move from the skirmish style of Rogue Trader, appears in practically every piece of Guard fiction written and pretty much defines the tactics of the entire Imperial Guard in the fluff.
In EPIC, Basilisks have a truly phenomenal range (well over the dimensions of the board!) and can throw down alot of firepower. They are the middle choice for me, without the Disrupt of Manticores or the Ignore Cover of Bombards, they provide “simple” firepower. As you can see I now have 2 Batteries of Basilisks painted up. These models are the old, sadly no longer produced, Forge World models. One gripe about them is the delicacy of the rear loading platform. The resin is wafer thin and quite often the railings break off. You may or may not be able to see this in the picture above, depending on how good your eyesight is! Apologies for the not so great picture quality.
The thing is I have never actually seen a Basilisk being played in 40k. Has anyone else?