Clockwise from top left: Nicholas Dirks, Action Bronson, John Brennan, Janet Mock Business Insider

Student activism has long been ingrained in the culture of college campuses, but protests about perceived discrimination over the past year have been especially tense.

These issues have been so pervasive at colleges that Barack Obama, Clarence Thomas, and Michael Bloomberg all warned about political correctness gone awry and the dangers of limiting free speech during their respective commencement speeches.

The Foundation for Individual Rights in Education (FIRE), a nonprofit organization dedicated to protecting civil liberties in higher education, agrees.

"One worrisome trend undermining open discourse in the academy is the increased push by some students and faculty to 'disinvite' speakers with whom they disagree from campus appearances," FIRE wrote on its website.

"While most noticeable around commencement season due to the high-profile status of many commencement speakers, disinvitations occur all year — and have been steadily increasing over the past 15 years," FIRE continued.

FIRE tracks these "disinvitation attempts" at colleges and publishes them in a database with details surrounding the revocation.

For the 2015-2016 school year, these individuals had speeches or performances canceled or interrupted beyond repair due to their beliefs or associations:

Ben Shapiro. Flickr / Gage Skidmore Brown University — Janet Mock

The TV host and transgender-rights activist withdrew from a speaking event after students protested, not because of the content of Mock's speech, but because pro-Israel group Hillel cosponsored the lecture.

California State University at Los Angeles — Ben Shapiro

Critics slammed the conservative writer and claimed his proposed lecture — about microaggressions, Black Lives Matter, and safe spaces — was not a debate but an attack. The university revoked his invitation, later allowing Shapiro to come to the campus after he threatened legal action.

"These aren’t diversity warriors," Shapiro told Breitbart News. "They’re jackbooted thugs."

University of California at Berkeley — Nicholas Dirks

The chancellor of Berkeley was scheduled to have a public discussion about the value of higher education, but the event was shut down after by students chanted and shouted over him. The protesters stated that he wasn't doing enough to help black students suffering hardships on campus and that his salary was too high.

University of Chicago — Anita Alvarez

The Cook County, Illinois, state attorney's speech was interrupted and did not continue because of both student and nonstudent protesters.

Protesters claimed that Alvarez was responsible for "state violence against Black and brown people in the City of Chicago" and failed to charge police officers, according to a press release from Black Lives Matter (BLM) Chicago, The Chicago Maroon reported.

Chicago has a history of extreme mistrust between its African-American community and police enforcement. Most recently, fury over the killing of 17-year-old Laquan McDonald, whom prosecutors claim police shot 16 times, reached Alvarez.

Anita Alvarez. Scott Olson/Getty Images University of Chicago — Bassem Eid

Students advocating for the Palestinian cause interrupted and shut down the political analyst and human-rights advocate's speech at the college. Eid, who is himself Palestinian, made comments that were seen as pro-Israel.

“Do not speak on behalf of the Palestinians again!” a student yelled during the event, The Chicago Maroon reported.

George Washington University — Action Bronson

The college revoked the rapper's invitation to perform due to claims his lyrics are misogynistic and that he has history of public transphobia.

Pressure on social media mounted and a petition to have Bronson removed from the lineup had hundreds of signatures by the time the administration agreed to revoke his invitation to perform.

Trinity College — Action Bronson

Another college did the same due to claims Bronson's lyrics are violent and sexually explicit.

More than 1,300 students signed a petition that stated: “Allowing Action Bronson to perform at Spring Weekend would create a psychologically harmful and drastically unsafe space for women, LGBTQIA+ students, and survivors of sexual assault.”

Hampshire College — Emily Wong

The school revoked its request for the physician at Massachusetts General Hospital's to give a commencement speech due to students' claims that she could not "directly address student concerns" regarding racial issues and transphobia.

Instead, Wong was replaced with activist Reina Gossett who was chosen “because her life and work engage the issues that have been raised by students around anti-blackness, transphobia, and sexual violence,” the school's press release read, according to The Chronicle of Higher Education.

University of Pennsylvania — John Brennan

The director of the CIA had an event substantially disrupted by protesters for his involvement in drone strikes in the Middle East.

After three instances where protesters interrupted and spoke over Brennan, the event ended early.

Suzanne Venker. screengrab via YouTube

A group of pro-Palestine protestors forced the mayor of the City of Jerusalem to end an event early. Instead, he convened with a small group of audience members.

Virginia Tech — Jason Riley

The professor who invited The Wall Street Journal (WSJ) columnist revoked his invitation over concerns of a controversy because he had "written about race issues."

Riley, who is black, also wrote a book in 2014, called "Please Stop Helping Us: How Liberals Make It Harder for Blacks to Succeed," which received some criticism.

Williams College — John Derbyshire

The writer and journalist was due to speak at Williams, but college president Adam Falk canceled the event, citing writings that some considered to be racist. Derbyshire published a bullet-point list in web publication Taki's Magazine about his thoughts on the black community that included:

(10a) Avoid concentrations of blacks not all known to you personally.

(10b) Stay out of heavily black neighborhoods.

(10d) Do not attend events likely to draw a lot of blacks.

Williams College — Suzanne Venker

The college revoked the author and social critic's lecture due to her criticism of feminism.

Venker, a self-described "anti-feminist," wrote an op-ed for Fox News explaining why women are supposedly having such a hard time finding husbands, called "Why men won't marry you."

"There was a time when wives respected their husbands," one portion read.