Today, Monday, Jan. 20, marks Martin Luther King Jr. Day -- a day to remember the iconic Civil Rights leader and all that he has done for racial equality and beyond in our country. Celebrities are taking to social media today to honor the great Dr. King and everything that he stands for. Read on to see Justin Bieber, Khloe Kardashian, Nicole Richie, Barack Obama and more honor the late Dr. King:

Some celebrities took to Instagram to celebrate Dr. King's words of wisdom:

While other A-listers celebrated MLK Jr. on Twitter: