Surface to air and anti-ballistic missiles. For purposes of completeness, we are including the conventional systems associated with Ballistic Missile Defense.
CIM-10 BomarcA long-range supersonic nuke-tipped SAM designed to vaporize Soviet bombers. As in, a single missile would vaporize entire squadrons of bombers. Looked something like a small, unmanned fighter aircraft, although "small" here is relative. Eventually phased out by the '70s, on account of being obsolete.
Nike seriesOne of the first SA Ms in US service and in fact anywhere in the world. Dates back to 1944, as the War Department wanted a way to shoot down jet aircraft more reliably. At one point they were widely deployed in the US to protect everything worth vaporizing; for you spelunkers and urban explorers out there, every major American metropolitan center has at least one abandoned Nike missile facility near its vicinity, provided that it hasn't been claimed by redevelopment. The successor to the initial MIM-3 Nike-Ajax was the MIM-14 Nike-Hercules, which was a substantial improvement in most respects and could even intercept ballistic missiles. Extra useless trivia: as they were funded at the same time, the Nike-Ajax missile and the Interstate Highway System are compatible: The minimum clearances in tunnels, overpasses, and such areas are designed so a Nike on a trailer can fit through them. All Nike batteries in the National Guard had one active duty officer. His job was to secure and arm the nuclear warheads that would be used to shoot down incoming Soviet bombers.
RIM-2 (originally SAM-N-7) TerrierAn early medium-range naval SAM, developed to provide an extra layer of defence between guns and carrier fighters. One variant had a 1-KT nuclear warhead. Capable of being carried on cruisers and smaller than the Talos, it was capable of being the first stage of a large launch vehicle and is today used as part of sounding rockets (sub-orbital rockets for experimental purposes) by NASA. Replaced by the Standard Missiles (SM) series.
RIM-8 (originally SAM-N-6) TalosA long-range (c.100nm) ship based surface-to-air missile, with two dedicated nuclear variants and one that was dual-capable. One of the earliest US naval SAMs, it was rather large, limiting the vessels it could be carried on to cruisers. Launched from a twin-arm Mk 12 launcher. Used in The Vietnam War, it shot down three MiGs. A radar-homing version was developed, also being used in Vietnam. It was retired in 1979 along with all the relevant ships bar the Long Beach class, which got new launchers instead. The remaining missiles were used as targets.
LIM-49 SpartanPart of Project Safeguard, a US ABM effort in the early '70s. A Nike derivative; it was designed to destroy warheads outside the atmosphere and it had a high-yield, 5Mt warhead. The problem was that detonating such a warhead at altitude would produce a massive EMP, imposing a radar blackout on the defenders...anyway, Safeguard was deployed, per the terms of the 1972 ABM treaty, to protect a US ICBM silo field in North Dakota. The system included some radars and command-and-control facilities, and a second type of interceptor, which might be one of the coolest missiles ever designed, the awesome...
SprintWhich didn't even receive a designation. Now, this was designed for terminal defense and endoatmospheric intercepts - in other words, like Spartan it was an ABM system. This required very fast reaction and flyout times, so the thing was insanely fast. And it had incredible acceleration, too; right out of the silo (the lid was fitted with explosives and not so much opened as fragmented; the missile was forced out of the silo by an explosive-driven piston) it hit 100 Gs! It was cone-shaped, and most aspects of its design were quite superlative. Average time for an interception was supposed to be around 15 seconds. Now, sure, you get far less time to pull off that intercept if you do it endoatmospherically, but when the warheads as well as the countermeasures and penetration aids they toss off reenter, they declutter, so you can tell them apart much more easily. Safeguard, however, well...per the terms of the treaty, the US was limited to a site protecting either the national capital or an ICBM silo field with 100 interceptors. (Originally both, but this was later amended.) So, the defense was only of very marginal value and it was rather obsolescent anyway (thanks to the "low-altitude" Topol ballistic missile). The Soviets actually had a counterpart system, around Moscow; an upgraded version (A-135) is still in place and operational.
AEGISThis ship-based system of phased-array radars, the SM series missiles and co-operative engagement capability (namely one ship can shoot the missiles of others) was originally designed to defend US carrier groups against a Macross Missile Massacre. In addition to firing on other ship's targets, each ship can also engage several dozen targets simultaneously. It was developed in the 1970s and started to be deployed in the early 1980s. AEGIS-equipped ships include the Ticonderoga CGs, the Arleigh Burke DDGs and a number of foreign warships based on the latter design. The AEGIS SPY-1 series radar in particular deserves special mention, being capable of pumping six million watts of radio energy down a particular bearing. This is enough that unshielded electronics (rare) on a "scorched" plane would be shorted out in short order. Two sailors tales abound: One of off-duty sailors wrapping a potato in tin foil, tossing it up in front of the operating radar, and receiving an insta-baked potato from the sky, and the other involving targeted aircraft crews having "FLKs" (Funny Looking Kids). Needless to say, this system usually idles at one third its max power.
RIM-66/67 Standard (SM-1/2)The newer SM series missiles only require target illumination for the last few seconds of flight, meaning that an aircraft that's been fired upon may not know it until it's too late to dodge or launch decoys. The very latest add an imaging infrared seeker as well, making them even more of a holy terror than they already were. These can also do double duty as anti-ship missiles, in a pinch. In recent years, the possible threat from Chinese anti-ship ballistic missiles is leading to an upgrade of the system including better missiles and radars.
AEGIS BMDA rather misunderstood system among many commentators, particularly the right-wing ones. The discussion turned very bad-tempered indeed. This four-phase system uses the existing RIM-161/SM-3 missile with upgrades (the SM-3 destroyed a wayward satellite in 2008) based on AEGIS warships, Patriot PAC-3 terminal defence interceptors and road-mobile SM-3s in Europe. It basically aims to provide faster defence against current and imminent Iranian ballistic missiles like the Shahab-3, although concerns have been raised over cost and flexibility if the Iranians get an ICBM faster than the US estimate. The concept was dreamed up by a team of experts who included musician Jeff "Skunk" Baxter (of SteelyDan fame).
["Star Wars"]Ronald Reagan's famous proposal for a missile shield in the 1980s, which would have involved space-based laser satellites to a large extent as well as kinetic impact vehicles and other unproven technology. The stated reason for this was a defence against a Soviet first strike, but the Soviets were seriously concerned that it would allow the US to destroy them and mop up any missiles they launched in retaliation. The end of the Cold War voided the reason for the system. Which was just as well since the technology involved was decades away from being workable, a fact that the Soviets were entirely unaware of.
MIM-104 Patriot familyThis high-altitude air defence missile family, entering service in the early 1980s, is the only ABM to have been used in real combat, namely against the "stretched Scuds" used by Saddam Hussein's Iraq against Israel and Saudi Arabia in 1991, and in the 2003 Iraq War against short-ranged missiles. Their performance in the former conflict has to be called very patchy. While they were able to divert missiles away from small targets to an extent, they couldn't do anything in regards to the area attacks on Israel and it took a lot of diplomatic effort to prevent Israel entering the war and destabilising the UN coalition. There were also deaths from successful hits. An issue that made it harder was the poor quality of their targets' construction, which meant the missiles had broken into clouds of shrapnel on atmospheric re-entry. This spotty performance is unsurprising given that the Patriot missile system was originally designed to defend against manned aircraft and cruise missiles, with ABM capability being a fairly hasty modification. In 2003, a US report concluded they probably got all 9 of the missiles Iraq launched into their areas, but the system also was involved in an embarrassing fratricide incident when an RAF Tornado was mistaken for hostile and destroyed. Their role in future conflicts would be terminal defence.
["Son of Star Wars"]This George W. Bush-era plan to defend the US and Europe against ballistic missiles from "rogue states" (e.g. Iran and North Korea) would have involved ten ground-based interceptors being deployed at each of three sites, two in the US and one in Poland. The latter and its associated omni-directional radar in the Czech Republic, aka "the third site" caused considerable diplomatic consternation with Russia, who feared that it would either damage its own deterrent and/or be a cover for a decapitation strike with medium-range missiles from Poland. As reason for their skepticism, Russia noted that neither Poland nor the Czech Republic is anywhere near Iran or North Korea. Barack Obama cancelled this particular deployment in September 2009, replacing it with AEGIS BMD, above. The Czech and Polish governments weren't particularly happy with this development, but AEGIS BMD is a much more mature technology than the still-experimental ground-based interceptors, as well as being more flexible given that the US Navy's dozens of AEGIS-capable ships can be positioned anywhere a ballistic missile defense could conceivably be needed on fairly short notice.