The WWE is the ultimate demonstration of "Here today, gone tomorrow."
Superstars are constantly cycled in and out of favor, and the spotlight, for an assortment of reasons. And as the wheels continue to turn for the WWE in its endless cycle of original content, it is quite common for WWE talents to fall out of sight for several months before resurfacing.
That is, assuming these talents are so lucky.
Jack Swagger was last seen on the September 3rd episode of RAW when he told former RAW general manager AJ Lee that he was going to take some time off since he felt he was better than what he had achieved in recent memory.
Swagger has since returned to WWE live show duty, reportedly with longer hair, (h/t WrestleNewz); however, no major character overhaul has been noticed to this point.
Christian suffered a mysterious shoulder injury and his last appearance on WWE TV came back in September when he sported a shoulder sling while showing heelish support of the (storyline) ban on Sheamus' Brogue Kick.
It is unknown when exactly Christian will return from injury, but Christian is surely a prime candidate for a Royal Rumble surprise entry come 2013.
Brock Lesnar's unique contract with the WWE allows him to work a limited schedule where the WWE can only use him for a certain amount of dates.
In order to navigate around Lesnar's limited dates, the WWE shot a storyline via Tout where Brock Lesnar announced that he had quit the WWE following a high-profile victory over Triple H at SummerSlam.
Lesnar is expected back come WrestleMania season, and the short list of potential opponents includes the Rock, the Undertaker and, unfortunately, Triple H.
Evan Bourne was suspended for 60 days for a second wellness violation and subsequently suffered a broken foot while out of commission.
Bourne should be pretty close to full strength, and he may be another superstar set to pop up at the Royal Rumble.
The Undertaker has been reduced to a special attraction performer, mainly at WrestleMania where he is still a novel draw.
Undertaker did make a rare TV appearance during RAW 1000, but he has not been seen since. It is unknown whether the Undertaker will work WrestleMania 29; however, there is a strong possibility that he will be featured at a major pay-per-view in 2013 in some capacity.