"Batman: The Animated Series" Super Post!

Even though DC had been using canon immigrants for as long as they had been around, the idea really caught on in the 90s.  Maybe it was because the internet was getting big then, or perhaps it was because of Harley Quinn, the poster child of canon immigrants, but whatever the reason, Batman: The Animated Series contributed several characters to the comics canon.  These characters are listed below, in the order of their first appearance on the show.

Renee Montoya

Nora Fries

Ferris Boyle

 

Ferris Boyle first appeared in the Batman: The Animated Series episode "Heart of Ice" (1992) as a part of Mr. Freeze's new origin (he was Victor Fries's boss).  His first comics appearance was Batman: Mr. Freeze (1997).

Summer Gleeson

 

Summer Gleeson first appeared in the Batman: The Animated Series episode "Heart of Ice" (1992).  Although she hasn't had a proper first appearance, she received a Gotham Gazette byline in Batman: No Man's Land - Secret Files and Origins #1 (December 1999) and appeared on tv in Batman: Gotham Knights #33 (November 2002), although this was a non-canon back-up story.

Grey Ghost

Mad Bomber

The Mad Bomber first appeared in the Batman: The Animated Series episode, "Beware the Gray Ghost" (1992), as a prop-making terrorist villain of the Gray Ghost.  His first comics appearance was in Batgirl #9 (June 2010), and later it was revealed that he was actually Clancy Johnson, who based both of his alternate personas on characters from the Gray Ghost tv show.

Harley Quinn

The Clock King

The Clock King is another of those interesting cases, because he actually started out as a comics characters; or, at least, a version of him did.  The Clock King first appeared in World's Finest Comics #111 (August 1960) as William Tockman, a villain who used clock-related gadgets in his crimes.
The Clock King that first appeared in Batman: The Animated Series, though (the episode "The Clock King" (1992), to be precise), is Temple Fugate, a guy who is obsessed with time and punctuality.  He first appeared in comics in Teen Titans #57 (May 2009) as a member of the Terror Titans.  This Temple Fugate has "absolute time sense".

Sewer King

Sewer King first appeared in the Batman: The Animated Series episode "The Underdwellers" (1992).  His only appearance in comics to date was in 52 #25 (October 2006).

Condiment King

Salvatore Valestra (aka Chuckie Sol)

Salvatore Valestra and Chuckie Sol appeared as two mob bosses in Batman: Mask of the Phantasm.  Their first comics appearance was in Justice League of America 80-page Giant #1 (November 2009) as a WWII-era mob boss named Valestra (Chuckie Sol was an alias).

Roxy Rocket

Farmer Brown


It wasn't just characters, though.  Several characters' designs made the jump as well:

Robin (Dick Grayson)

Left: Dick Grayson as Robin
Middle: Dick Grayson as Robin on Batman: The Animated Series (1992)
Right: Dick Grayson as Robin in "Nightwing: Year One" (Nightwing #101, March 2005)

Clayface

Clayface (Basil Karlo) was originally just a guy that could change the shape of his face (Detective Comics #40, June 1940). Later, there was Matt Hagan, who was a man made out of clay.  In Batman: The Animated Series, though, he became a monster made out of clay, which inspired the appearance of a new Clayface, Cassius Payne (the son of Basil Karlo and Sondra Fuller, another Clayface), who first appeared in Batman #550 (January 1998).

Robin (Tim Drake)

Left: Tim Drake's first comics costume
Middle: Tim Drake on The New Batman Adventures
Right: Tim Drake's One Year Later costume (the colors are in memory of Superboy), starting with Teen Titans #34 (May 2006)

Mr. Freeze (alternate reality)


As well as certain storytelling elements:

Killer Croc's condition

When Killer Croc first appeared, he was noted as having a rare skin condition. In Batman: The Animated Series (1992), however, his appearance was caused by a mixture of human and reptile DNA.  I don't know yet the first time it changed, but in Batman #608 (December 2002), his condition was said to be regressing, causing him to gain a pronounced jaw and a tail.

Batman and Zatanna's former relationship/Batman as a former trainee of Zatara

These two plot points first appeared in the Batman: The Animated Series episode "Zatanna" (1993) and later came to light in Detective Comics #824 (December 2006) and #833 (August 2007), both of which were written by Paul Dini.