As the name suggests, Titans adapts DC's Teen Titans to the small screen. That said, it makes several changes to its titular teenage superheroes. Most of these put the comics' cheesy concepts more in-line with the show's dark, angst-ridden approach. Few are more affected by this treatment than Beast Boy.
The team's resident class clown sees some drastic tweaks in this version. Comic book loyalists likely have a cow (pun intended), especially since several of these amendments affect him on a fundamental level. More broadly, it raises confusion as to the show's place in the larger DC Universe.
Warning! Spoilers ahead.
6 His Skin
The most noticeable change is the skin tone. In the comics, Beast Boy's skin and hair are both green. That's held true for all subsequent animated appearances. Sadly, it's not the case with his live-action counterpart.
The Beast Boy of Titans looks like a normal guy with pale skin. True, he still sports green hair, but the rest of him has a regular pigment. The showrunners probably went in this direction for budget reasons. After all, it'd be expensive to keep him green all the time, whether it's through makeup or CGI. They take the same route with Starfire. On the upside, he still turns green when he transforms. Better late than never.
5 Once A Titan, Always A Titan
Beast Boy was formerly part of the Doom Patrol. He was the runt of the litter, but nevertheless a valued member of the team. He later left to join the Teen Titans, but he still wore his old costume. Here, though, that resemblance is just a coincidence.
Gar stayed with the other misfits at Niles Caulder's house, but he never became a long-term member. In fact, he might as well be in an entirely different universe. The Doom Patrol members never acknowledge this temporary guest in their own show, and their development doesn't seem to line up with the Titans series. That's to say nothing of the radical difference in style. They barely ever sport costumes or fight crime as a traditional superhero team, instead tackling their own psychological and existential issues. Clearly, Beast Boy is meant to stay in the Titans' lane.
4 His Origin
This goes hand-in-hand with the Doom Patrol liberties. After his parents' death, Gar lived in the Congo, where he contracted a deadly disease from a primate. Niles Caulder helped him through this sickness, though the process left the kid with transformative powers. That's why he was supposedly living with the Doom Patrol. However, this revised origin leaves a few figures out.
In the comics, it was Gar's scientist parents who brought him to the Congo. They were studying extinct animal species, but their son contracted a rare disease called "Sakutia." Their solution was to turn him into a monkey, which is supposedly immune to the illness. Yes, really. This inadvertently gave him his shape-shifting powers. Needless to say, it would have been tough to sell this backstory in a realistic setting.
3 His Attitude
The comics' Beast Boy is often the source of comic relief. He's the most like a normal teenager in that he's usually messing around. He loves playing games and pulling pranks on his teammates. This behavior makes him borderline cartoonish at times. Obviously, the showrunners didn't want such a lighthearted character in their gritty adaptation.
As a result, Beast Boy is another angst-filled figure in a show rife with them. He's not quite as full of navel-gazing self-loathing as the other characters, even snapping out the occasional quip. That said, he's still darker than what fans are used to. Becoming a mindless beast during his transformations is emblematic of that. His powers are no longer a fun gimmick, but a curse.
2 A Limited Selection
As the name suggests, Beast Boy's powers are based on animals. He can change into countless creatures at will, making him unpredictable both in and out of combat. His palette isn't even limited to Earth. Some stories see him morph into alien animals. Truly, the sky's the limit.
Unfortunately, the limits are lower in Titans. In this show, Gar can only turn into a tiger at first. The second season gives him a snake form on top of this, but that's it. Even these transformations are rare, as he does much of his fighting in his human shape. Again, this may come down to budget cuts. Alternatively, the writers may want to illustrate his character progression through his abilities, having him gain more forms as he grows more comfortable with his powers. Either way, the Beast Boy of Titans fails to live up to his name.
1 No Acting Career
Most superheroes have occupations outside of crime fighting. Beast Boy has several such hobbies, but the most unique is acting. Gar occasionally appears in television shows and commercials. He even moves to Los Angeles to pursue that dream. As the most outgoing Titan, he would naturally be comfortable in the spotlight. That's why adaptations like Young Justice keep this hobby when tackling his character.
Sadly, it's yet another aspect that's not here. Titans never touches on Beast Boy's acting career. That's not to say he's totally detached from the entertainment industry--he breaks into stores to steal video games. Being in one of these works just never occurs to him.