An unnamed dog dies soon after 16m mark. Its not lingered on and not too graphic as long as you don't freeze on it (in comparison to the human gore) but a yelp is heard alongside it
The first season ends with Omni-Man leaving Earth after his battle with Mark. When we next see Nolan in the second season, he already fathered another son.
Throughout the series, Cecil, Donald, and the GDA are spying on the Grayson family from across the street, which could be taken as stalking in a sense.
Every Viltrumite in a way is a victim of systemic abuse, joining the machine to perpetuate it.
Finale of season 3 has it spelled out by the mouth of one in particular.
Episode 7 at 29:41 (trigger phrase “you wouldn’t dare), a shockwave either injured/kills many small rodents and birds. Only the birds are shown to be dead. A scorpion is crushed to death earlier in the series also
The dragon does not die, as it’s later revealed to be a shape-shifting human, who briefly appears at the end of the show as a teaser for the next season.
there is 100% giant spiders in this show, without going in to much detail, the main villain of this episode uses his powers to befriend giant spiders and uses them to fight the main heroes.
Monster Girl briefly mentions that because of her young body, she only gets romantic advances from boys going through puberty or people who are registered sex offenders. No pedophiles appear in person, and Monster Girl is not sexualized.
In Timestamp 39.00 to 39.45 a character (Donald) cuts himself to test if he is a robot as he was supposedly killed in the prior season. Although I am not that affected by the scene, might be triggering to some. There are a few other instances of "cutting" in fights between the viltrumites, as they use blades and their hands to cut Mark and Omni-man. take care during the scenes where they fight the other viltrumites, especially in the city scene.
On top of the occurences in seasons 1 and 2, 4 hands of 3 different characters get crushed in the span of this one episode of season 3. (One of said hands is prosthetic)
There are several scenes where the main character gets beat up pretty badly, making his breathing laboured. The main character is also unable to breathe in space, but this does not get brought up a lot.
As of the end of season 3: YES A LOT.
This happens often enough and unexpectedly enough that if this is a deal breaker, you're better off skipping the show.
It happens both on and off screen, explicitly and implicitly, to secondary and background characters alike.
Spoilers for the Atom Eve special episode:
The antagonists are highly deformed, have exposed muscle and organs and can morph their limbs in a grotesque looking manner due to experimentation.
throughout the show there are a few moments where hands get broken/squished/cut, but none of it is directly on the fingers. there's a few scenes where feet are squashed by large heavy objects/creatures but again no toes are shown and it isn't directed at them.
a couple of people are dropped from high places throughout a few episodes, some are saved but there's a lot that aren't. just generally be weary of this.
Technically not abduction, but potentially a difficult watch anyway if child abduction is a trigger for you. In the Atom Eve special, a baby is separated from it's mother at birth (for it's own safety) and [Further spoilers!] It's later revealed that the mother is being kept barely alive to create more children like the first, who are then raised obviously without being able to interact with their mother considering her condition.
Seen in episode 8. (Spoilers) Mark attempts to save a mother and her child from a falling building, but the building falls on all three of them. No body or gore of the child is seen, but her death is heavily implied as she is not seen again and her mother was crushed.
Season 1 near the end. Not exactly sacrificing himself to save someone else, but sacrificing his own life so another himself can live the life he couldn't. This character COULD have lived longer if he hadn't gone through with thus entire plan.
Season 3, episode 7, a member of the main cast sacrifices themselves to take down one of the villains in a way that leaves no ambiguity to whether or not he dies despite the lack of a corpse.
Powerplex's motivations are rooted in the fact that his sister and niece were killed during Omni-Man's rampage (they turn out to be the mother and child Invincible tried to save from the falling building), and he accidentally kills his own wife and son.
A certain shrinking character in their shrunken form crawls inside of someone during a fight with the Lizard League. When they expand, they are unable to escape and seemingly gets eaten alive.
Throughout Season 3, Mark believes that putting villains in prison is the only way to keep them from hurting any people as a way of coping with his brutal murder of Angstrom Levy from last season.
Multiple characters are written with traits that viewers with mental disorders may connect with, such as Robot/Rudy's high IQ but lack of emotional understanding/tact, showing signs of mental instability, multiple characters having depressive episodes/traumatic experiences/memories, etc. However, as far as I remember it's all just subtext in the writing and as of the release of season 2 I don't believe any character has been explicitly stated as having any particular mental illness or disorder.
Episode 6 of Season 3 features the villain Powerplex, who wants revenge on Invincible for the accidental deaths of his sister and her daughter during the Chicago battle during the Season 1 finale. It's made incredibly clear how the trauma has caused both Powerplex and even his wife to snap and swear revenge on Invincible, to the point where Debbie comments on how mentally unstable Powerplex is.
One minor villain has a focus on correcting perceived shortcomings of the human body. A fairly major plot thread involves a disabled character trying to obtain a new, non-disabled body.
A certain character expands while inside of an enemy in an attempt to kill him. It doesn't work and they are crushed and basically eaten. You only see this from the outside
A character specifically asks another character not to prevent their planned death in episode 7, even if not direct suicide a warning seems appropriate.
In the Atom Eve Special, two parents grieve over the loss of a stillborn baby. The doctor informs them of their baby being fine, but it is revealed that the baby was swapped with another one at birth.
Mark expresses disgust when his friend expresses attraction for Omni-Man (who is secretly Mark’s father) which is mistaken for homophobia. A teen boy sexually harasses a teen girl and calls her a lesbian derogatorily for not reciprocating.
A disabled character's body is treated with disgust by other characters in one scene. On a meta level, their body is portrayed very grotesquely in the art style similar to the way the gross-out gore is, and [SPOILERS] the character chooses to die rather than continue living in their disabled body, which could definitely be a triggering plot point to someone sensitive to ableism.
it isn't confirmed if they die or not in season 1 but a character gets into a life or death situation where they don't come out very well in episode 6. they don't come back to the show after this and are only mentioned maybe once or twice.
Darkwing is depicted as a black man in this series, but he's not one of the first characters to die a gruesome death. Likewise, Black Samson gets horribly injured in the fight against Battle Beast, but he recovers.
a few of the teenage characters are seen making out on a bed, a few characters are caught in the shower together implying they were doing sexual things but it's not shown. its implied that Omni-Man and Debbie are having sex in one episode but it isn't shown at all either. mainly just noises. none of it is graphic.
When Conquest admits to Invincible how lonely he feels due to being so sadistic and powerful that the other Viltrumites fear him, Conquest says that sometimes he feels so alone that he wants to cry, but can't.
a few cars are thrown at heroes and villains throughout the show, a story is created in episode 5 where a main character uses "being hit by a bus" as a cover for what really happened to him.
Animated blood and gore feature prominently, especially (but not exclusively) during action scenes. Expect *large* amounts and a *lot* of detail
Skipping gory scenes is not a viable option, as many of them are critical to the plot
Once you learn to expect any and all violence to result in gore, you may be able to look away beforehand. That said, the aftermath will often be be visible for multiple shots and the show often cuts to it later with little or no advance warning
Blood and gore will also appear in the recaps at the starts of episodes with even less advance warning than usual
Be careful