After a decorated playing career with the Foxes, Nixon returned to Grace Road in October 2017, leading the club to the knockout stages of the Vitality Blast in 2020 and the quarter-finals of the Royal London Cup in 2022.
Nixon said in a statement released by the club: "I am immensely proud of my time at Leicestershire and would like to thank the players, both past and present, staff and most of all the fans for the unconditional support I have received during my tenure. The club will always hold a special place in my heart, and I wish them all the best for the future."
Henderson said in the statement: "Paul has been a true servant to Leicestershire County Cricket Club since he first joined the club in 1988, in two stints as a player then as Head Coach since 2017. He's shown relentless commitment, enthusiasm and passion during his time as head coach and has been a fantastic ambassador for the club. We wish him every success in the next steps of his career.
"Our attention now turns to the process of finding a new head coach to work alongside Alfonso Thomas and James Taylor, whilst ensuring we also remain competitive for the second half of the 2023 season.
"The squad possesses a wealth of exciting young talent and has shown some encouraging progress in the early stages of the summer. We believe we have established an effective coaching structure and we are keen to build on our strong culture and values.
"Whilst it has been a difficult fortnight for both parties, now is a time for collectiveness. We as supporters, players and staff need to stick together to ensure that our trajectory as a club continues upwards in the months ahead."
Leicestershire are second in Division Two of the County Championship but have struggled in the Blast this year, losing 12 of their 14 fixtures, including a 92-run defeat at the hands of Northants and a 71-run loss to Derbyshire.