Sin Piedad (2011) (Spanish for "No Mercy") was an annual professional wrestling major event produced by Consejo Mundial de Lucha Libre (CMLL), which took place on December 16, 2011, in Arena México, Mexico City, Mexico and replaced CMLL's regular Friday night show Super Viernes ("Super Friday"). The 2011 Sin Piedad was the tenth event under that name that CMLL promoted as their last major show of the year, always held in December. The main event of the show centered around a long running storyline between Blue Panther and the Casas wrestling family, represented by El Felino in this instance. The two wrestled in a Lucha de Apuesta, hair vs. hair match where the loser of the match would be forced to have all his hair shaved off. The show featured four two out of three falls six-man tag team match and one tag team match with representatives from CMLL's Mini-Estrella division.

The Mexican wrestling company Consejo Mundial de Lucha Libre (Spanish for "World Wrestling Council"; CMLL) has held a number of major shows over the years using the moniker Sin Piedad ("No Pity" or "No Mercy"). CMLL has intermittently held a show billed specifically as Sin Piedad since 2000, primarily using the name for their "end of the year" show in December, although once they held a Sin Piedad show in August as well. CMLL has on occasion used a different name for the end-of-year show but Sin Piedad is the most commonly used name. All Sin Piedad shows have been held in Arena México in Mexico City, Mexico which is CMLL's main venue, its "home". Traditionally CMLL holds their major events on Friday Nights, which means the Sin Piedad shows replace their regularly scheduled Super Viernes show. The 2011 Sin Piedad show was the tenth show to use the name.

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