Wild Weasel
Wild Weasels are the aircraft crews who try to sniff out and kill enemy anti-aircraft defenses ahead of other air missions, as well as the pop-culture name for that mission. They show up in some flight sims and a few pieces of war literature, but not quite enough to be their own trope; nevertheless, while stories of fighters-versus-SAMs aren't quite as glamorous as hot fighter-on-fighter action (and thus gets way less exposure in popular culture), they're still a very important component of aerial warfare, not to mention an eternal part of the Vietnam War for pilots. In short, they handle Escort Missions where the main threat is a Macross Missile Massacre from surface-to-air missiles instead of enemy aircraft.
If I Can't Have It, Neither Can You: Surface-to-Air Threats
The whole purpose of surface-to-air missiles and guns is to deny the airspace immediately above and around the launcher to enemy forces. These are covered under Modern Battlefield Weapons, but for the most part they fulfill the same role: to make life hell for bomber and fighter-bomber crews. As the Yanks With Tanks learned during the Vietnam War, trying to bomb targets without first suppressing air defenses can lead to truly horrific loss ratios. The vast majority of US aircraft lost over 'Nam were to ground fire and strategic SAM batteries, in particular the feared SA-2 Guideline, the most widely-deployed long-range SAM. Antiaircraft gunfire and most infrared-guided missiles like the SA-7 and the Redeye could be avoided by flying high enough (4,000 feet to avoid the worst of the small arms for a fast-moving fighter, and 20,000 feet was usually plenty to dodge the heavy AA guns), but that puts you right in the center of the engagement envelope for SA-2s--and, as a certain Francis Gary Powers learned, you can't outclimb a missile. Unless the SAM commander was especially careless, there was no way to stay out of their engagement envelope while attacking the high-value target they were guarding. What was worse, the strategic SAMs were often located far behind the front line, meaning that the traditional RTS counter--namely, a ground assault--could not be used. (Besides, no self-respecting pilot would allow himself to owe those smelly ground-pounders down in the mud any favors.) So the only way to reach those pesky SAM Sites was, you guessed it, aircraft. You know, the very aircraft that the SAMs were designed to counter.
Into the Den: Meet the Weasels
Actually, the idea was basic enough: fit a "Wild Weasel" aircraft with basic radio-detection equipment, add in an additional couple of wingmen, and have it accompany the flight of bombers. At some point, some enemy search radar--say, a "Fan Song" radar for the SA-2--will light up your formation. The Weasel chases down the direction of the radar signal with his wingmen right behind him; if the SAM locks on to him and launches, it's go low and evade (SA-2s were notoriously inaccurate below 3,000 feet). Keep this up until it finds the launch site and/or radar and hits it with rockets and cannon. After that, its wingmen perform their own strikes on the site to make sure it's dead, all while the bombers proceed serenely unmolested by the SAM site. What Could Possibly Go Wrong?, indeed?
(Not coincidentally, the unofficial motto of the Wild Weasels was "YGBSM", for "You Gotta Be Shittin' Me!", reportedly the response of the first Weasel pilot Electronic Warfare Officer when he learned just what his mission entailed.)
So, in 1965, the US Air Force authorised a special unit of aircraft and aircrew to tackle this mission. Flying two-seater F-100F fighter-bombers, they marked the first time in the history of aerial warfare where aircraft had to seek out and neutralize the threat of surface-to-air missiles like the SA-2 Guideline. The F-100 proved unsuitable and was replaced successively by the F-105G Thunderchief and the F-4E Phantom, two of the most iconic Vietnam-era aircraft (the Navy used A-4 Skyhawks and A-6B Intruders to cover their own strikes). At the start, the aircraft had to perform two missions: "Iron Hand" to suppress enemy radar sites (by launching Shrike missiles and forcing them to stay off the air) and "Wild Weasel" to seek out and kill the missile batteries themselves. As time went by, both terms were merged under the Wild Weasel name; technically, the mission is called "SEAD", for "Suppression of Enemy Air Defenses", while the planes are called "Wild Weasels", after the very aggressive predator that would chase its prey into its den if it had to. The first Weasel "kill" came in December 1965, as recounted in the pilot's own words.
Shrikes and Standards: Antiradar Missiles
One of the biggest problems with the first Weasel missions was actually finding the radar site to attack. Even with the radar broadcasting all the way, the direction-finding equipment was pretty primitive; it couldn't tell you how far the radar site was, and it wasn't precise enough to triangulate on a specific site. Plus, the radars and missiles tend to be disguised (like, say, under a thatched roof). Finding a radar site often meant flying low in the direction of the radar, praying that some machine-gunner on the ground doesn't get lucky, and trying to notice when your direction-finding gear is telling you that the radar's suddenly behind you. Not particularly easy.
Then, somebody got a great idea for an anti-radiation missile (ARM): instead of the aircraft chasing down the radar site and having to find it, why not fit sensors into a missile that would seek out the strongest source of radar signals and home in on it? And thus, the AGM-45 Shrike was born. The whole idea was that you could close in on the radar and launch your Shrike missiles without having to pinpoint its location; after the Shrike hits the radar, the Weasel and its wingmen follow up with rockets and bombs to make the site is well and truly dead. In practice, the Shrike was a bit of a letdown: its warhead was too small to do anything more than damaging the radar antenna (which was easily replaceable), its range was quite short (15 miles versus 30 miles for an SA-2), and each individual missile could only home in on one kind of radar per mission. Its biggest problem was that it only could attack an actively broadcasting radar: North Vietnamese SAM crews learned to turn off their radars when a Shrike was on the way, causing it to lose guidance, and turn it back on after the missile had gone wild. Nevertheless, the Shrike was useful enough and cheap enough that it became the primary tool of the Wild Weasel flights.
The Shrike was quickly followed up by the Navy-built AGM-78 Standard. These were bigger, faster, and--most importantly--had a function that allowed them to "remember" the location of a SAM site, so that they had a chance to hit even after the radar had shut down, albeit with reduced accuracy. However, they were much more expensive than the Shrike and much heavier--a given aircraft couldn't carry as many Standards as Shrikes. The AGM-78 was mainly used as a supplement to the AGM-45 in Vietnam.
Exploiting the Terrain: Geo Effects IN THE AIR!
The whole business of SAM hunting was a fair bit more complicated than just lofting Shrikes and Standards at whatever Fan Song radar lit up the sky. One big problem was that of range: a single SA-2 weighed 5,000 pounds, and most of that was rocket propellent; that gave it a far longer reach than the short-ranged Shrike missiles. The antiradar missiles would rarely put an entire SAM site out of commission for long: the standard SA-2 battery consisted of six launcher vehicles in a "Star of David" formation around the radar van, plus a small fleet of support vehicles and stockpiled missiles. The missile would only kill the radar van, if it hit at all (and if the radar was turned on--always a big if). Plus, there was the question of flight time: the SA-2 was fifty percent faster than the Shrike, and still significantly faster than the Standard, meaning that a SA-2 could launch its missile, guide it to its target, and turn itself off to avoid the incoming ARM.
So, despite the addition of the Shrike and the Standard to the Wild Weasel arsenal, flying SEAD often entailed closing in on the radar site and hitting it the hard way, with unguided bombs and rockets. Just getting close enough was a real challenge: aircraft had to skim the treetops and hide in valleys to avoid radar exposure. Low-altitude flight, in turn, meant increased vulnerability to shoulder-fired missiles and antiaircraft guns, the number-one cause of aircraft losses in Vietnam. Add in the many tips and tricks on the propagation of radio waves, jamming, chaff, ECCM, and you could see why Weasel crews call it "a game of chess in 3-D, and the opposition cheats". Because Wild Weasel missions take place at low altitude, terrain matters. (This is also why what applies for land-based SEAD doesn't always work for attacking navies: over a flat ocean, there are no canyons to hide in. Barring stealth technology or truly exceptional ECM work, you're not getting within 30 miles of a competent radar screen without being detected.)
Post Vietnam
The US piloted Wild Weasel techniques in Vietnam, so most cases of pop culture that do feature SEAD missions are drawn from/inspired by the Vietnam-era missions. However, in the roughly forty years since the war, the fighter-versus-SAM conflict has continued in various parts of the world, although not on the same scale as Vietnam. The most immediate example came just after the US pulled out from Vietnam, during the 1973 Yom Kippur War, where new Egyptian and Syrian SA-6 missiles and ZSU-23/4 antiaircraft guns hurt the Israeli Air Force very badly; as the IAF learned the hard way, what worked against the long-ranged SA-2 wasn't necessarily applicable against the short-ranged SA-6. The Israelis would return the favor in 1982, where imaginative use of decoy drones over the Bekaa Valley and some very intense training post-1973 paid off nicely (30 SAM sites and 80 Syrian fighters destroyed versus zero Israeli losses).
For the US, the F-4G Wild Weasel-dedicated variant and the AGM-88 HARM, the successor to both the Shrike and the Standard, came into service, where they proved very deadly against Soviet-made SAMs in Libya and Iraq. As a measure of just how far the Wild Weasel mission has come since its birth, note that Baghdad's air defense system in 1991 was estimated to be triple the thickness of Hanoi's. It was comprehensively smashed in a matter of weeks, thanks in no small part to new weapon systems like cruise missiles and the F-117 stealth fighter. The USAF is one of comparatively few services to maintain a dedicated Wild Weasel platform, the F-16CJ; most other air forces have taken the US Navy approach of fitting EW pods and antiradar missiles to multirole aircraft for the SEAD role.
The advent of armed remote controlled drones combined with improvements to stealth technology has further changed the nature of Wild Weasel missions. As drones are unmanned and relatively cheap, they can be used to great effect in distracting air defenses. Drones (which are no-where near as fast or dangerous as figher-bombers, and are not attractive targets for SAMs) crowd the radar screen and draw fire while stealth aircraft power in and attack. While there is no such thing as a perfect stealth, when they are visible on radar they produce very small signatures, comparable to drones. In practice it makes it incredibly difficult for SAM crews to know what to shoot at, and what is actually attacking them.
Similarly, the advent of AWACS air-born radar/control centres and space base surveillance technologies has greatly reduced losses in anti-SAM missions. Knowing where SAMs are positioned practically eliminates the need to place aircraft in harms way. Modern terrain skimming cruise missiles can hit with superb effectiveness at extreme ranges and are next to impossible to shoot down. In response to this, SAM crews move their positions constantly and place radar reflectors, although this does not protect them from commando units marking targets. Similarly, once a SAM site goes active and gives its position away, modern GPS, inertial guidance and AWACS control can guide a weasels missiles to where they need to be with a great degree of certainty, regardless of radars being active.
As with most things in modern combat, the advantages are all with the attackers. Even assuming that you have no knowledge of a SAM site's location and have no ability to kill it from safe range, wild weasel missions are not as dangerous as they once were. Stealth technology allows planes to get into position with decreased risk, and improved on-board computers allows for faster tracking and (combined with smarter missiles) the ability to strike at targets even when radars are off.
In practice, SAM systems by themselves can only really slow down a large, modern airforce. The only real defense is a similarly sized and funded air force, and even then the defenders are still at a huge disadvantage, as they have to spread their forces around the clock.