There have been multiple Blue Beetles in comic books... at least four that I know of (or at least, can differentiate between). The first two both had a secret identity of Dan Garrett (sometimes spelled with one "t"), and had a similar costume, but that's about it.
The first one was published by Fox Publications, making his first appearance in Mystery Men Comics in 1939. This Dan Garrett was a rookie policeman who would take "Vitamin 2X" to give him super-energy, which primarily manifested itself with super-strength, although there's some super-speed in there as well. Other than that, he was like a lot of non-powered "mystery men" of the day. Dan was teamed with an older cop, Mike Mannigan, who was out to capture and arrest Dan's costumed identity.
Actually, Dan began his costumed career without benefit of powers... the Vitamin 2X came later, along with his bullet-proof costume. For the most part, his adventures weren't too out of the ordinary, fighting suit-and-tie crooks of the type many costumed crimefighters did, but apparently sales of the comics he was in were good enough to prompt a radio program based on his adventures. I've listened to a few of these, even though the quality of the episodes that I was able to find made listening difficult. In these radio programs, he came off much as a knock-off of the similarly-named Green Hornet (indeed, the Hornet was probably an influence, although BB had no Kato of his own).
Dan's love interest was Joan Mason, a pretty blonde reporter (copying from Superman here), and she appeared in her own solo stories after a bit (just as Lois Lane did).
The comics stories, as I said, weren't all that impressive. I've read a number of them, and for the life of me, I couldn't tell you any details about any of them, other than what I already mentioned.
When Fox Publications folded, the character was sold to Charlton Comics, who reprinted a few of the original Beetle's adventures in their anthology titles, but in 1964, they revived and revised the Beetle in his own comic book.
This version of the Beetle cast Dan Garrett as an archaeologist who found a mysterious blue scarab in Egypt, and when he said the magic words "Kagi Dha," he'd be transformed into the Blue Beetle, with a range of powers that included super-strength, the ability to fly, super-vision, and the ability to cast energy blasts. His stories were played a lot for laughs, as you can imagine by one story being titled "The Giant Mummy Who Was Not Dead!" This version of the Beetle lasted until 1966, when he was replaced by Ted Kord.
This replacement story may have been the first time in comics that the concept of a legacy hero really was presented! While DC's revivals were inspired by their Golden Age counterparts, this was the first time a hero's identity was more or less directly transferred from one character to another. Ted Kord was a student of Dan's, and was currently a genius inventor. Ted and Dan were investigating Ted's uncle Jarvis, discovering that he was building an army of super-androids on Pago Island. Dan changed into the Blue Beetle to defeat Jarvis, but gave his life in the process. Ted decided to take on the identity of the Blue Beetle to honor his former teacher, although since he didn't have the scarab, he had to create a version of his own.
It was this version of the Blue Beetle that I first encountered, on the cover of an issue of the Rocket's Blast Comic-Collector. I didn't know anything about him at the time, other than I thought he looked cool as hell. This version of the Beetle was drawn by Steve Ditko, and probably designed by him as well. Without powers, this Beetle relied on a few gadgets, notably the "BB Gun," which could emit a blinding burst of light or a compressed air charge, as well as his flying "Bug," a ship that looked like a gigantic beetle, complete with legs that could move to grab objects. The Bug was kept in a secret underground lair accessible through an underwater tunnel. I'm sure the Bug was an influence for the Turtle's shell in the Wild Cards books.
This Beetle fought much more interesting crooks than his predecessors, including the Mad Men, who wore multicolored outfits with masks that resembled the later Creeper's face, as well as Punch and Jewelee, a husband-and-wife criminal team that focused on jewel robberies.
This version of the Beetle lasted only a few years, although he was revived in a one-shot story in Charlton Bullseye, which teamed him with the Question. His next appearance was in a few comics published by AC, including one that brought the Dan Garrett version back to life! This story claimed that Dan had been both of the first two Beetles, with the second version being a reincarnation by the gods, leaving Dan with no memory of his original life. The other AC comic teamed up the Beetle, the Question, Captain Atom and Nightshade as the Sentinels of Justice.
It was about the same time this was published that DC Comics purchased the rights to the Charlton superheroes (as a present to Dick Giordano, who had edited most of the original Charlton superhero books -- this didn't include E-Man, nor did it include the full rights to Thunderbolt, but that's a mess in and of itself). DC didn't use any of the Charlton heroes until Crisis on Infinite Earths, where they had Ted in possession of Dan's scarab (which had been lost on Pago Island). He wasn't able to access its abilities, but it did help protect him from the Anti-Monitor's shadow beings.
Not too terribly long after Crisis ended, DC brought out their own Blue Beetle comic book. This book took many of the elements from the Charlton book, but also brought about some changes. Ted Kord was now in charge of Kord Industries, a high-tech company not unlike Stark Industries, and was relocated to Chicago. None of his original supporting cast survived the move from Charlton, and he was given a new cast of characters, including one policeman who was convinced Ted had something to do with Dan's death on Pago Island, and relentlessly pursued him on that point.
Ted became one of the founding members of the new Justice League at the end of the Legends mini-series, which helped a lot after his new title was cancelled. In this new Justice League book, Ted became friends with Booster Gold, and together they'd get themselves in and out of trouble, oftentimes dragging the entire League with them. There were a lot of laughs to be had in this book, but subsequent writers started making the laughs more at Ted's expense, almost as if they didn't feel he brought much to the table as a hero. During the "Death of Superman" storyline, when the League fought Doomsday, Ted suffered injuries that put him into a coma. Later storylines had him gaining weight, discovering he had a heart condition (which he constantly complained about).
Perhaps it was a blessing in disguise when DC had Ted executed at the hands of Maxwell Lord in Identity Crisis, although this was the first straw that led to the breaking of the camel's back that was my buying new comic books (what a labored metaphor that was, eh?).
The fourth and, so far, final Beetle has little connection with the previous ones. Jaime Reyes was a teenager living in Texas who found a blue scarab which, initially, he's not aware is capable of providing him with powers when it fuses to him as he sleeps. This scarab is apparently supposed to be the same one Dan Garrett had, and while it's initially portrayed as magical, it's later revealed to be a technological construct made by the alien race called the Reach. The scarab, which gives Reyes pretty much any technological power he needs (at least, it appears that way, making it sort of an ultimate Iron Man armor), later starts trying to take Reyes over so the Reach can use him for their conquest of earth. Later, the scarab is damaged and Reyes is able to take control of it.
I've only read a few stories of this latest Blue Beetle, and while he's a pleasant enough character, I can't say that I'm a big fan.
He fared much better for me in Batman: The Brave and The Bold, where he's kind of a trainee of Batman's (this show also had two episodes in which Ted Kord appears, voiced by Wil Wheaton!). The Reach storyline was presented in this series, although it has Jaime gain control without damaging the scarab to accomplish this.
The second season of Young Justice also features the Reyes version of the Beetle, and in fact, the Reach storyline is also used here, much more extensively than in B:TBATB.
As you may have guessed, I'm a fan of the Ted Kord Beetle the most, probably because he was "my" Blue Beetle. As a young adult, I started tracking down the comics in which he appeared, learning more about him as I went, including reading his origin. I didn't read any of the second Dan Garrett stories until probably 20 years ago, and then only a few of them, while I was able to read a lot of the original Garrett stories from Fox in the past few years.
As an aspiring comic book writer, one of my faults was that instead of coming up with "done-in-one" sample ideas to submit was that I'd come up with ideas to revive characters instead. Only one of these ideas was ever submitted, for reviving Nova (before Marvel did their own revival). One I never submitted was a way I felt would re-invigorate the Blue Beetle concept, after the first DC series was cancelled.
I figured this: The Bug was an aviation innovation that wasn't matched by anything... so why not move Ted Kord (who'd had Kord Industries pretty much destroyed at the end of his run) to Seattle, Washington, where aviation is one of the biggest industries? I figured that Ted would start a new business, perhaps "Kord Innovations," which would basically be involved with the design and testing of new air technologies. Along with the move would come some new villains appropriate for the area... I think one of them was to be outfitted with a suit of flying armor capable of supersonic speeds. I also figured there'd probably be other villains from the DCU that hadn't been used in a while that could've relocated there. Green Arrow, of course, had already been moved to Seattle some time ago, but I figured his current portrayal would keep him from the same crimefighting the Beetle would be involved with, although a team-up would've been inevitable.
I have no idea what Beetle, if any, is being used in the "New 52" DCU. As I don't have any real strong feelings about the Jaime Reyes version, I wouldn't be adverse to Ted being restored to life somehow (I recall that a Booster Gold series had Booster traveling back in time to try to save Ted's life, but I believe that it was unsuccessful). Even if someone wanted to do it, though, I don't know if I'd give it a chance. Ted's adventures need a balance of humor and seriousness to really work. In a lot of ways, his portrayal should owe a lot to the first ten or so years of Spider-Man, with Ted being serious in his civilian identity, and more of a wisecracker as the Beetle.