Tournament:Mega Smash Mondays

Mega Smash Mondays (MSM) was a regional Super Smash Bros. Ultimate tournament series (formerly ) held every Monday at Thunder Studios in Long Beach, California. It debuted in May 2015 and since then became one of the most popular weekly tournaments in the United States, with the number of entrants often reaching a hundred. It is run by, the 2GGaming crew, and streamed on 2GG's Twitch channel. The VoDs are later uploaded on 2GG's YouTube channel.

Due to 2GGaming's partnership ending with eSports Arena, Mega Smash Mondays was moved to Thunder Studios in Long Beach, California, beginning with Mega Smash Mondays 131, which took place on January 29th, 2018. As a result, doubles were brought back beginning with Mega Smash Mondays 132 which occurred the following Monday.

Because of the COVID-19 pandemic, the series was paused after Mega Smash Mondays 232 on March 9th, 2020, before resuming as an online weekly with Mega Smash Mondays Online 1 on April 20th, 2020. It returned to physical tournaments on July 6th, 2021. After Mega Smash Mondays 242, the series was discontinued. A spiritual successor,, would be launched on January 9th, 2023.