As we all know, men's rights activists are grossly misunderstood. On the surface, the men's rights movement looks to be about getting equal rights with respect to things like adoptions and custody disputes, but actually, the movement is primarily a coordinated attack on women. After all, nothing says "we just want men to have equal opportunity" like threatening violence against women (content warning: rape, death threats).
With the men's rights movement coming into its own more and more, it's been the background motivating an increasing number of adventurers. I playtested a sun elf warlock who has my variant pact with the Patriarchy and this new men's rights activist background yesterday - it was loads of fun.
From page 125 of the Player's Handbook:
Every story has a beginning. Your character's background reveals where you came from, how you became an adventurer, and your place in the world.
Here's a new background for the increasingly popular men's rights activist:
Men's Rights Activist
You have spent your life oppressed by women. You have watched other men share this fate, and you have formed a small brethren with some of these men to serve as the sole force for progress towards true gender equality in the world.
Choose a cause to focus on. Are you going to be the one to champion the cause for male adventurers to get the same increased recognition and pay as their less talented female colleagues? Are you going to fight for magical teachers to revamp their mentoring to focus only on the underserved needs of restless male wizards-to-be? Perhaps you will be the one to combat the discrimination men face in not being allowed to unconditionally unleash their barbaric rage? Figure out how to channel your anecdotal experiences to make necessary systemic progress.
Skill Proficiencies: History, Insight
Languages: Dialects of Abyssal and Draconic in which all sentences begin "Well, actually"
Equipment: A tinderbox, a scroll of the collected offenses against men from a dying male elder from the town you grew up in, a set of fine clothes, a pouch that automatically disappears whenever anyone allied with you asks you about how much money you have, and 30 gp you have inherited
Feature: Authority on the Hierarchy of Privilege
When you meet someone, you are able to immediately determine every way in which they are better off than you. You are also able to recall knowing someone who is even more privileged than they are in the town you most recently visited.
Men's rights activists are shaped by their experiences with the women they have known and their imagined ideas about women they have never met. Their reflections on half thought-out what-ifs affect their mannerisms and ideals. Their flaws might be that fiction often affects their reality as much as their obviously fully unbiased observations.
d8 Personality Trait
- I envy a particular woman's position in life and constantly belittle the unnecessarily hard work she has had to spend her whole life to get there.
- I can find common slights against even the most dissimilar of men and empathize with them completely.
- I see the potential for discrimination against men in every event and action. Women try to ruin us, we just need to see it.
- Nothing can shake my paranoia.
- I slander women in almost every situation.
- I am tolerant of other people as long as they are men.
- I've enjoyed high status and undeserved aid from society. Easy living coddles me.
- I've spent so long interacting only with men that I have little practical experience relating to women.
- Equality. Everyone, not just men, benefits from equal opportunity. (Good)
- Power. I hope to one day push women to the lowest class in society. (Evil)
- Change. We must help bring about the changes the world needs to advance us all. (Any)
- Awareness. The path to power and self-improvement is through spreading knowledge. (Neutral)
- Responsibility. It is my duty to protect and care for the men who cannot do so themselves. (Lawful)
- Respect. I must prove that I can do anything I want despite the oppression of my gender. (Chaotic)
- I would die before admitting a woman deserves her lot in life more than I do.
- I will someday get revenge on the woman who wronged me.
- I owe my life to the man who enlightened me about the oppression men face.
- Everything I do is for the common man - man, not person.
- I will do anything to protect the men I know.
- I seek to destroy the unfair ways society advances women.
- I judge women harshly, and give myself a pass on all my faults.
- I put too much trust in those who enlighten me about another way men are oppressed.
- My self-righteousness sometimes prevents me from noticing my hypocrisy.
- I am inflexible in my thinking.
- I am suspicious of strange women and expect the worst of them.
- Once I notice something oppressing men, I become obsessed with it to the detriment of everything else in my life.
 Interestingly enough, feminism champions these causes.