<Li> Karen Gillan as Ruby Roundhouse, a commando, martial artist, and dance fighter who is Martha's avatar . Roundhouse is proficient in karate, tai chi, jujutsu and capoeira, and her only weakness is venom, such as that found in various animals in the game . Similar to Bravestone, Roundhouse is the archetypically intelligent, athletic, beautiful, and scantily clad video game heroine of the story . She is credited as "Martha". </Li> <Li> Nick Jonas as Jefferson "Seaplane" McDonough, Alex Vreeke's avatar . McDonough is a mysterious guide, adventurer, and pilot in the game, who waits for and joins the other avatars as they attempt to escape Jumanji . McDonough's strengths are piloting and making margaritas . His only weakness is mosquito bites, which is bad for him since the jungle is teeming with mosquitoes . He is credited as "Alex". He lives in a treehouse built and once occupied by Alan Parrish (previously portrayed by Robin Williams and Adam Hann - Byrd in the 1995 film Jumanji). </Li> <Li> Bobby Cannavale as Russel Van Pelt, a corrupt explorer seeking to control the "Jaguar's Eye", whose power he is demonically possessed by . He is the boss of the film's video game scenario; Jonathan Hyde played a different version of Van Pelt in the 1995 film . </Li> <Li> Rhys Darby as Nigel Billingsley, an NPC guide in the game . </Li>

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