loans McCormack joined Aston Villa, under Roberto di Matteo, on 4 August 2016 for £12 million on a four-year deal. Three days later, he was included in Villa's starting lineup for their 2016–17 Championship opening fixture away to Sheffield Wednesday, a 1–0 loss. He scored his first goal in a 1–1 draw with Huddersfield Town at Villa Park on 16 August. On 21 January 2017, Villa manager Steve Bruce revealed that McCormack had been dropped from the first team squad for "continually missing training", adding that "he is nowhere near fit enough to play and be involved". Twelve days later, he joined fellow Championship team Nottingham Forest on loan until the end of the season. After making the loan move, McCormack admitted that he had once missed training when he had been trapped in his home by a faulty electronic gate. He scored on his debut for Forest in a 5–1 loss at Norwich City on 11 February. McCormack made himself unavailable for "personal issues" in March, as Forest struggled against relegation. McCormack made only two EFL Cup substitute appearances in the early part of the 2017–18 season after returning to Villa. On 29 September 2017, he signed for A-League club Melbourne City on loan until January 2018. He made his debut in the season opener on 6 October, starting as his team defeated Brisbane Roar 2–0 at the Melbourne Rectangular Stadium. Fifteen days later, he scored his first goal, a free kick to win a home game against the Wellington Phoenix. On 28 October, he scored both goals of a 2–0 win at Adelaide United. After the game, he told the media that he was pleased to be in scoring form again. On 22 November, it was reported that McCormack had been dropped from the Melbourne City squad for being "exceptionally late to training". After returning to Villa, McCormack was still frozen out of the team due to his disputes with Bruce. In May 2018, it was revealed that his annual salary of £2.3 million would have a bonus £1 million added if Villa were promoted, despite him not playing a league match for them that season. On 20 September 2018, McCormack signed a one-year loan deal with A-League club Central Coast Mariners FC. He played alongside the Olympic sprinting champion Usain Bolt for Central Coast, and assisted Bolt's first goal in an official football match. On 5 January