There's trademark, copyright, and patent lawsuits and trolls in abundance. I'm too lazy to google the links for ya, but here's a few that come to mind:

Candy Crush, as Truerror mentioned. There's a balance here, and though King was clearly on the wrong side of the line, I wouldn't call them a troll.

Tim Landel ("Edge" trademark). Definitely a troll.

The SpryFox lawsuit was an example of a good lawsuit against geniune copyright infringement.

Nintendo was sued over the 3DS's glasses-free 3D screen, by some gent at Sony. If I recall correctly, Nintendo lost the lawsuit - though they might've appealed.

Most major MMOs pay patent fees over some dumb 'virtual world' patent. This includes World of Warcraft being threatened, and paying (nuisance lawsuit - cheaper to pay than to fight).

Every rumblepack-enabled controller has to pay fees to some "inventor", except Nintendo, because Nintendo successfully "invented" (and brought to market: The N64 rumble pack) the invention before the inventor did.

The Carmack Reverse was patented (and not by Carmack. Another company discovered it first, a few years earlier)

Marching Cubes, patented

MP3 music files, patented (not unjustly patented - they were patented by the creators, it just sucks that they are so ubiquitous and proprietary)

Microtransactions in games - patent troll'd. Someone (or more than one) was going around threatening to sue app developers for using microtransactions, unless they pay an extortion fee, instead of suing Apple or Google directly.

Thankfully, the USA has recently improved the laws around patent trolling, to make it harder to do "<x> but with a computer!" patents, and in some cases are even making the patent trolls have to pay for the other side's legal fees if they lose the lawsuit.

AskPatents (a StackExchange sub-site), is trying to help make it easier to combat patent trolls, by crowd-sourcing users to find prior-art.