Goalkeeper Kelleher stepped in for his maiden league appearance when Wolverhampton Wanderers were beaten 4-0 in December.
Phillips’ debut in the division came back in October, when the centre-half started the 2-1 victory over West Ham United at Anfield.
Williams, meanwhile, was handed a first Premier League opportunity by Jürgen Klopp when he featured throughout the 2-1 home win against Tottenham Hotspur.
And the Academy graduates’ achievements were recently recognised by the Premier League as they received a commemorative Debut Ball apiece at the AXA Training Centre.
Introduced in 2015-16, the memento is given to all homegrown debutants who were developed at the academy of a club in English football for three years or more at the time of their first appearance.