Clifford Samuel Avril (born April 8, 1986) is a defensive end for the Detroit Lions of the National Football League. He was drafted by the Lions in the third round (92nd overall) of the 2008 NFL Draft. He played college football at Purdue.

Avril was born in Jacksonville, Florida and attended Clay High School in Green Cove Springs. He was Second-team All-State selection as a defensive end his senior season, after recording 80 tackles, including 11-for-losses, nine sacks and four pass breakups.

Avril then attended Purdue University where he started 12 games at strong-side linebacker and 23 at left defensive end. After converting to defensive end in his final two seasons at Purdue, he recorded 30 of his 35.5 tackles-for-losses and 12.5 of his 13 sacks from the left end position.

In 2004 he appeared in all 12 games, including four starts made 36 tackles (23 solo, 13 assists), including 3.0 for loss and 0.5 sacks, with one pass breakup and one forced fumble. In 2005 he appeared in 10 games, including four starts and had 33 tackles (21 solo, 12 assists), including 2.5 for loss. In 2006 he started all 14 games, the first four at linebacker and last 10 at defensive end and recorded 84 tackles (51 solo, 33 assists) 15.0 tackles-for-loss, six sacks and six pass breakups, two forced fumbles, one fumble recovery and one interception.