The fifth and final series of the British science fiction programme Primeval began on 24 May 2011 and concluded on 28 June 2011 after airing six episodes.

Primeval follows a team of scientists tasked with investigating the appearance of temporal anomalies across the United Kingdom through which prehistoric and futuristic creatures enter the present.

The disappointing viewing figures led to Primeval not being renewed for a sixth series even though both the cast and the production team were eager to continue.

Despite the low ratings, critical reception of the fifth series was positive, with praise for the visual effects, character development and many homages to classic science fiction.

[4] According to Primeval co-creator Tim Haines, the overarching plot of the fifth series was exploring the mysterious motives of Philip Burton (Alexander Siddig), tying them into the main storyline and explaining why Matt Anderson (Ciarán McMenamin), revealed in the fourth series to be from the future, was working for the ARC in the first place.

[8] The third episode of the fifth series was innovative in terms of plot for Primeval as it saw Matt travel back in time to Victorian London through an anomaly.

[4] The storyline of the episode saw Matt and Emily Merchant (Ruth Bradley) track down a dromaeosaur loose in the Victorian era, mistaken as a murderer and as the infamous folklore figure Spring-Heeled Jack.

[4][8] In addition to featuring time travel, the episode also served to deepen the relationship between Matt and Emily and to, on account of its Victorian setting, "play up the melodrama".

Haines also revealed the return of the future predators, a signature creature of Primeval absent since the third series, though in a "slightly different guise".

[11] The swimming dromaeosaur featured in Primeval was revealed by Haines in a panel discussion on 7 February 2011 to be the Cretaceous theropod Balaur.

[28] The finale's broadcast on ITV (21 July 2012) met with the lowest ratings in Primeval history, with only 1.38 million viewers (a 10.2% audience share).

Owen criticised the plotline of the first episode as "weak and predictable" and felt that the cast of the fourth and fifth series was "by far [Primeval's] weakest line-up".

Owen had a mixed perception of Primeval overall, though he praised the CGI of the series he felt that it "never achieved its huge potential to be Stargate-meets-Jurassic Park", that it failed to deliver substance in-between its action sequences, and that while it at times had fun ideas it was usually unable to implement them effectively.

[32] Contrary to Owen, Robert McLaughlin of Den of Geek gave the first episode a positive review, considering it a "great, action-packed premiere" for the fifth series, "mixing the right amount of intrigue, monsters, explosions and expositions".

[33] He found the fourth episode to be akin to a "run of the mill 1980s monster in the shadows affair" but found it to "[rise] above the generic" for its subplot revolving around Connor and Abby beginning to plot against Philip; he particularly praised the cliffhanger at the end of the episode as the first on the series in a long time to be "actually tense".

[38][39] He greatly praised the final episode as the series "going out with a bang" and commended it for the reintroduction of the future predators and for tying up many loose ends, as well as Alexander Siddig managing to "avoid too many clichés" in his villain performance.

[47] He considered the series to be "going out on a high",[47] but felt that the final episode was somewhat mediocre, finding it "rather dull" with "some flashes of greatness"; although "spectacular" at points and with good character moments, Golder felt that the episode disappointed as a satisfying dramatic conclusion, lacking in surprises and revelations and being too predictable.

[4] Members of the cast at the time remained hopeful that a new series could get commissioned; Hannah Spearritt stated in an interview that Primeval has "been known to come back from the dead before".

[52] While speculation still surrounded whether a sixth series would be made, a North American spinoff, Primeval: New World was announced in September 2011.