As pointed out by others, the first three minifigures are genuine LEGO (with the second having perhaps a few custom accessories). The fourth is not a LEGO minifig. It may include some genuine LEGO elements (legs, hands, etc), but the militaristic accessories are not LEGO elements. This appears to be a custom minifig sold at one time by Modern Brick Warfare.
The figure holding the lightsaber is composed of the head and hair of Anakin Skywalker from the Clone Wars series:
the torso of Luke Skywalker as a Jedi Knight:
and a pair of dark gray legs on medium gray hips:
The clone figure has the torso of a shock trooper from Ep 3.:
But I couldn't find the helmet.
Zovits identified most items, the missing helmet is a Stormtrooper Type 2 helmet from an AT-AT driver, which is likely also where the legs from the Anakin/Luke mix figure as identified by Zovits come from.
As an added bonus: the torso of this AT-AT driver is used on the middle stormtrooper on the second row from the front, so you have the complete figure.
These are identified from left to right.
Series 18 of Lego Minifigures has that first policeman. Here is the exact minifigure.
The second one appears to be from Series 9 of Lego Minifigures. Here is the exact minifigure.
The third policeman appears to be LEGO Policeman with Riot Helmet Minifigure with a different head. The head might be Minifigure, Head ...
this appears to be
Robot Devastator 4 - Red Eyes
from the following sets
8107: Fight for the Golden Tower
8112: Arachnoid Stalker or 8115: Dark Panther
Partlist for Devastator
Bricklink part list
I talked to a Lego expert on the lego.com online chat. He told me that this particular lego head was an exclusive part for the Build a Minifigure bin and gave me the part number for it 6257472 mini figure head #2829. I didn't know there were exclusive parts in the minifigure bin, I wonder if this is something new. He seemed quite surprised when he found ...
You can find all the minifigs heads ever made, with the date of release, in the BrickLink catalog: http://www.bricklink.com/catalogList.asp?pg=1&catString=238&catType=P&v=2
Please note that I have already sorted the minifigs heads in the link above by year released, however on the first two pages of the results you will see heads where the year ...
Yes they are. The top figure is made out of these parts:
Head: Item 3626bpb0220
Hair: Item 3901
Torso: Item 973c19 but with yellow hands
Legs: Item 970c00
The bottom figure has the same torso as the top figure, and these parts:
Head: I cannot find this as a LEGO provided minifig head print, but there are several ways to customize LEGO heads, like ...
48379 is the part number for the torso piece. 2003 would be the copyright date for the LEGO trademark.
They are both promotional items which were distributed with McDonald's Happy Meals.
Bricklink: 7923-1 (White Soccer Player #4)
Bricklink: 7917-1 (Blue Basketball Player #22)
Legs and torso are from a Unitron figure: http://www.bricklink.com/catalogItem.asp?M=sp048
The red bandana has appeared in almost 100 sets (often pirate-themed), while the head and hands are generic and could be from any number of sets as well.
Looks like the Comic-Con 2012 exclusive Shazam / Captain Marvel: https://www.bricklink.com/v2/catalog/catalogitem.page?M=sh042#T=I
From the quality of the lighting in the photo it's hard to be definitive but if I had to guess I'd say this isn't genuine Lego but a reproduction figure or knock-off (KO).
The torso for this figure is 973pb0321c02 Torso Town Vest with Pockets and Striped Tie over White Open Collar Shirt Pattern / White Arms / Yellow Hands.
It comes in several minifigures, but none of them are like yours, so I think this is composed of other parts ( a MOC figure) and not directly from a set.
Brickset has a list of 89 Fabuland figures.
Bricklink has a list of 93 Fabuland figures, these include
variations in accessories.
Fabuland.net states there are 142 characters in 80 variations and has
a full list of characters including which sets they were sold
If you were to collect one of every animal type (excluding colour variations) you would at ...
Knight's Kingdom II - the guardian (picture taken from bricklink)
I searched on Bricklink catalog under, 'minifig leg assembly' using the keyword, 'brown,' using thumbnails. Only had two pages to look through.
At last, I have your answer. The figure is from a "Giant Pre-School Loc Bloc" set, likely the "Playground" one shown in the picture.
Nearly a month later, while doing unrelated research, I found "Giant Brix Blox", a second possible source of these types of figures;
It makes since given that sources claim Loc Blocs & Brix Blox were both imported ...