• Years of the 21st century-related lists (28 C)

0–9

• 2000s-related lists (15 C, 24 P)
• 2010s-related lists (16 C, 39 P)
• 2020s-related lists (16 C, 42 P)

A

• Lists of animals described in the 21st century (3 C)
• Lists of armed conflicts in the 21st century (18 C, 20 P)

C

• Lists of The Colbert Report episodes (10 P)

D

• Lists of 21st-century disasters (2 C, 4 P)

F

• Facebook-related lists (3 P)

G

• Lists of songs in Glee (TV series) (7 P)
• Google lists (1 C, 18 P)

I

• Instagram-related lists (2 P)

L

• Lists of 21st-century trips (67 P)
• Lists of Internet-related superlatives (21 P)

M

• Meta Platforms-related lists (2 C, 2 P)

N

• Netflix lists (2 C, 4 P)

P

• Lists of 21st-century people (4 C, 61 P)

S

• Lists of sovereign states in the 21st century (3 P)

T

• Twitter-related lists (8 P)

W

• Lists about Wikipedia (9 P)

Y

• YouTube-related lists (1 C, 10 P)

A

• List of accidents and incidents involving the DC-3 since 2000
• List of American television programs currently in production
• List of Animal Crossing media
• APRA billion streams list
• List of awards and nominations received by Ashlee Simpson

B

• List of best-selling albums of the 21st century

C

• List of Canadian retail closures (21st century)

F

• Forbes Global 2000
• Forbes list of the most valuable football clubs
• Forbes list of the most valuable MLB teams
• Forbes list of the most valuable MLS clubs
• Forbes list of the most valuable NFL teams
• Forbes list of the most valuable NHL teams
• Forbes list of the most valuable sports teams

G

• List of giant squid specimens and sightings (2001–2014)
• List of giant squid specimens and sightings (2015–present)

H

• List of human spaceflights, 2011–2020
• List of human spaceflights, 2021–present

I

• Historical annual reformulations of the influenza vaccine

K

• List of Keith Olbermann's special comments
• List of killings by law enforcement officers in the United States prior to 2000

L

• List of international presidential trips made by Viktor Yanukovych
• List of saints canonized in the 21st century
• List of songs recorded by Alice in Chains
• List of unsuccessful terrorist plots in the United States post-9/11
• List of lunar eclipses in the 21st century

M

• List of charges in United States v. Manning
• List of crewed Mars mission plans
• List of monuments damaged by conflict in the Middle East during the 21st century
• List of most-subscribed Twitch channels
• List of most-visited websites

O

• List of Organisation of Islamic Cooperation organizations
• List of all-time Overwatch League win–loss records

P

• List of destinations served by ferries from the port of Piraeus

S

• List of ships attacked by Somali pirates
• List of songs featured in Shrek
• List of 21st century sinkholes
• List of solar eclipses in the 21st century
• List of songs about the September 11 attacks
• List of spacewalks since 2025
• List of Spotify streaming records
• List of most-streamed artists on Spotify

T

• List of most-followed TikTok accounts
• List of Tony Awards ceremonies
• TV Guide's 50 Greatest TV Shows of All Time
• TV Guide's 100 Greatest Episodes of All-Time
• List of most-followed Twitch channels

V

• Videos and audio recordings of Osama bin Laden

W

• List of Wii games with traditional control schemes