This is an animated gif of Gandalf from Lord of the Rings shouting "You Shall Not Pass" at the Balrog Demon that has been chasing them.
This is an animated gif of a guy about to open the door before some dude comes and kicks it down. While all of this is happening, the text "Knock, Knock! Who's there? It's reality!" is shown on the screen. Obviously, it's an analogy gif for how hard reality can be. This is from the movie "The Transporter" (2002). The guy who launches himself into the door is Jason Statham playing the character Frank Martin.
This is an animated gif of a member of the bomb squad dancing before he bends down to pick up two rifles and points them up into the air while a controlled explosion goes off behind him. I'm guessing that this is a US military member in Afghanistan or Iraq.
This is an animated reaction gif of singer Britney Spears turning her head with a shocked / confused facial expression, as if to say "WTF did he just say / do"? You can use this whenever somebody says something that is nonsensical or downright weird. I think this is from American Idol, where Britney Spears is a judge.
This is an animated gif of a black dude at a WWE (formerly known as the WWF) show freaking out / in shock as the wrestler The Great Khali enters the ring. Obviously, he's not a big fan of the 7 ft 3 in giant. This can be used as a reaction gif whenever you're feeling shocked, dismayed or distraught.
This is an animated gif of Michael Scott holding a speaker above his head while singing "Everybody Dance Now!". Scott is a character in the US version of the hit TV show The Office. He is played by Concord, Massachusetts actor Steve Carell, who has starred in movies such as The 40-Year-Old Virgin and Evan Almighty.
This is an animated gif of Sherlock Holmes bluntly saying "Yes, thank you for your input" before slamming the door in Dr. Anderson's face. The actor is Benedict Cumberbatch and the TV show is called Sherlock. This particular episode was called "A Study in Pink". Great gif to use whenever you think somebody's opinion is worthless.
This is an animated gif of Danny 'Danno' Williams being lost for words / speechless. This can be used as a reaction gif whenever somebody says something so stupid that you don't even know where to begin. Danno is a character in the TV show Hawaii Five-0. He is played by actor Scott Caan, who is from Los Angeles, California.
This is an animated gif of actress Emma Stone sarcastically giving a thumbs up. This can be used as a reaction gif whenever you want to express sarcasm towards somebody or something that they've said. Stone is 24 years old and she's from Scottsdale, Arizona.
This is an animated gif of Stephen Colbert sitting still with a straight face while red, white and blue balloons fall down around him. Colbert is a political satirist from Washington, D.C. He is the host of the TV show "The Colbert Report". You can use this as a reaction gif whenever you're not amused by something that everyone else is celebrating.
This is an animated gif of actor / comedian Eddie Griffin sitting on a couch and eating popcorn. This scene is from the 2002 movie Undercover Brother, where he played the main character Anton Jackson. This can be used as a reaction gif whenever something suspenseful or overly exciting is happening. Eddie is from Kansas City, Missouri.
This is an animated gif of Admiral Ackbar from Star Wars Return of the Jedi shouting "It's a trap!". This is a meme that is often used in relation to men posing as women. Lately, it has been used a lot as a reaction gif for whenever a girlfriend/wife tries to trick you into admitting/doing something that they'll inevitably get annoyed about.
This is an animated gif of Maurice Moss from the TV show "The IT Crowd". In this scene, he takes out a drink and some popcorn and puts them on his desk before smiling and saying "GO". This can be used as a reaction gif whenever drama in unfolding.
This is an animated gif of Professor Utonium from the Powerpuff Girls making OP. The running joke is that OP (the original poster) is "always a faggot". Hence the reason somebody has edited this scene of the Professor to make it look as if he inadvertently spilled a substance called "faggot" when he was making the OP.
This is an animated gif of Dr Evil and his cohorts laughing manically. This is from the Austin Powers film series. Great reaction gif for when somebody says something stupid or far fetched. Not sure what the context is because I haven't watched the movie in years.
This is an animated gif of an Asian girl laughing before pulling a serious facial expression. This can be used as a reaction gif whenever you want to express fake laughter. Usually used when somebody says something that you don't find particularly funny.
This is an animated gif of Karl Pilkington pointing and shouting "Bullshit!". Karl stars in the show "An Idiot Abroad". This is a great reaction gif to use whenever somebody is lying or a commonly-held social truth is found out to be untrue.