Castagna has signed on for a further two seasons, while Townsend has put pen to paper on a new one-year deal.
Tough midfielder Anthony Miles, who was named as Richmond VFL’s best and fairest, has also signed on for another season.
Richmond’s General Manager of Football Talent Dan Richardson praised the trio for their work this season, especially the premiership duo.
“We are really pleased with Jason’s on-going development and his work-rate, both on and off the track. His pressure around the ball is a highlight and his brand of footy was very much aligned to the team success this year,” Richardson told richmondfc.com.au.
“Jacob played a significant role for the team in all our finals games, none more so than the Grand Final. He is a strong competitor and, having found his niche up forward, we expect he will continue to build on this in 2018 and beyond.
“Anthony is highly regarded by his teammates and the Club as a whole. His strong work ethic, contested ball-winning ability and commitment to the team are second to none. Despite limited opportunities in 2017, he is a proven AFL player, who will continue to make a significant contribution to the Club.”
Castagna played all 25 games for Richmond in 2017, and finished fourth on the club’s goalkicking chart with 26 majors.
Townsend played the final five games of Richmond’s season after waiting for his first opportunity in round 22, and went on to kick 16 goals.
Miles played just five senior matches for the Tigers this season, although he led the VFL side to the grand final.