PBS NewsHour (7pm, UNC-TV) - In this special report, Robert MacNeil and Jim Lehrer look back at the Watergate scandal that began in the summer of 1973, transforming American politics and journalism and ultimately ending a presidency. MacNeil and Lehrer led PBS coverage of the Watergate hearings, co-anchoring all 250 hours of the proceedings. They share their memories and talk about how the experience forged their friendship and their journalistic partnership.

How Nature Works (8pm, National Geographic Channel) - A documentary looking at the interconnectivity of the millions of plant and animal species on Earth.

Nikita (8pm, CW) - Amanda puts her final plan into effect as the third season ends. Her diabolical plot places Nikita (Maggie Q, left) in a life-threatening situation and forces her to choose between saving Michael or herself.

Shark Tank (8pm, ABC) - The fourth season ends with two new back-to-back episodes. In the first, sharks hear about a jewelry line created by women with military experience and we get an update on the Scrub Daddy investment. At 9, two business school grads have an idea for a translation app, and an 11-year-old pitches his all-natural dog treats.

Fatal Justice (8pm, Lifetime) - A woman seeks justice for her family after her niece is seriously injured during a robbery. When the police fail to help, she takes matters into her own hands and learns that the men involved in the crime may also be responsible for her brother's murder 10 years earlier..

Real Time With Bill Maher (10pm, HBO) - Zach Galifianakis is Maher's mid-show interview guest tonight. Other guests include Richard Haass, president of the Council on Foreign Relations, S.E. Cupp, documentary filmmaker Michael Moore and journalist Andrew Ross Sorkin.

Merlin (10pm, Syfy) - An old flame reenters Mondred's life and tests his loyalty to Arthur.

Who Do You Think You Are (8pm, NBC) - Rita Wilson takes a big fat Greek journey to trace the highs and lows of her father's life. Her travels also take her to Bulgaria.

Grimm (9pm, NBC) - Nick (Dave Giuntoli) and Monroe (Silas Weir Mitchell) investigate the murder of a spice-shop owner and the victim's sister may prove to be an ally for Nick. Also, Capt. Renard recruits Adalind to hex Hank and Sgt. Wu gets caught up in Adalind's scheme.

Fringe (9pm, Fox) - A case is familiar to Peter but brand new to the rest of the team.

Fairly Legal (9pm, USA) - Kate mediates a dispute between a fishing boat captain and an injured deckhand. Elsewhere, Nicastro encourages Lauren to date.

Blue Bloods (10pm, CBS) - Danny faces a moral dilemma over whether to arrest a suspect who may be linked to a robbery.

Merlin (10pm, Syfy) - In the Season 4 finale, Camelot is lost and Arthur is unsure that he should be king. Merlin tries to boost Arthur's confidence by leading him to the legendary Excalibur sword and encouraging him to remove it from the stone.

Who Do You Think You Are (8pm, NBC) - Actor Blair Underwood traces his lineage in a genealogical journey that includes a DNA test, a trip to Africa, and articles that reveal the hardships and unforeseen triumphs of his ancestors. Meredith College history professor Dr. Dan Fountain (right) was consulted and worked with Underwood for the episode. Read more about Fountain and his experience on the show.

A Gifted Man (9pm, CBS) - Michael's high school girlfriend arrives at Holy Neuro with a grave condition and he has trouble accepting the limits of what he can do to help her.

Great Performances: Memphis (10pm, UNC-TV) - A performance of the Tony Award-winning musical about a white high school dropout in 1950s Tennessee who becomes a disc jockey in order to promote the music of a black singer he has fallen for.

Merlin (10pm, Syfy) - Merlin tries to treat a mysterious illness that's inundated a distant village, but soon suspects something sinister is at play when even his spells are unable to cure the sick.

Blue Bloods (10pm, CBS) - Danny's emotional state causes concern for his wife and kids when he relentlessly searches for a killer who murdered an undercover detective. The case is personal for Danny because the victim was a Reagan family friend.

A Gifted Man (8pm, CBS) - Michael's clinic colleagues rush to operate on him after he exhibits signs of a dire condition requiring immediate medical attention.

Chuck (8pm, NBC) - Chuck and Sarah mull over the next phase of Carmichael Industries, while Casey gets  more deeply involved in his forbidden romance with Gertrude Verbanksi. Also, an intellectually elevated Jeff begins to scrutinize some of the crazy happenings at the Buy More.

Supernatural (9pm, CW) - Sam helps a teen girl search for her missing father, who is also a supernatural hunter. Meanwhile, Dean tries to take down Dick Roman (James Patrick Stuart).

Merlin (10pm, Syfy) - In the Season 4 premiere, Morgana summons Callieach to rip apart the fabric between the worlds of the living and the dead, unleashing creatures that kill anyone they touch. It's up to Arthur and the knights to save the kingdom while Merlin attempts to restore order to the world.

Blue Bloods (10pm, CBS) - Erin's informant is murdered and she blames herself for his death. So she teams up with Danny to find out who killed him.

Confessions: Animal Hoarding (10pm, Animal Planet) - A former rock musician's dogs may be more important to him that his own daughters, and a woman refuses to choose between her family and her 99 pets.

Shark Tank (8pm, ABC) - Redneck millionaire Jeff Foxworthy (left) takes a seat with the Sharks  tonight. Also, Vincent Pastore, who played Big P-, uh, make that Salvatore Bonpensiero on 'The Sopranos,' pitches an idea.

Who Do You Think You Are (8pm, NBC) - In the second season finale, actress Ashley Judd explores her ancestry, zeroing in on her colorful paternal great grandmother and finding connections to the Union Army and America's first settlers.

Blue Bloods (10pm, CBS) - Linda's runway-model niece and a reporter are poisoned at a fashion show. Designer Marc Bouwer appears as himself.

Merlin (10pm, Syfy) - The Season 3 finale finds Camelot crumbling under the control of Queen Morgana and Morgause's immortal army. While Arthur, Lancelot, Elyan, and Percival prepare for a counterattack, Merlin rushes to retrieve the Excalibur sword from the Lake of Avalon. This season finale leaves you more time to watch ...

Camelot (10pm, Starz) - Arthur's pursuit of Guinevere proves unrewarding. Also, Leontes and Kay recruit a new warrior they believe they can trust, and Arthur and Merlin contemplate a dinner invitation to Morgan's castle.

Real Time with Bill Maher (10pm, HBO) - Guests are Colin Quinn, Katty Kay, Eliot Spitzer, and Andrew Sullivan.

Whatever, You're So Wrong (11pm, Hallmark) - Martha Stewart's daughter Alexis Stewart and Jennifer Koppelman Hutt in a new late night talk show where they tackle topics about everyday life as well as serious issues. The third season of 'Whatever, Martha!' (also with Alexis and Jennifer) debuts at 11:30pm. In that show, the two women basically critique old Martha Stewart episodes (and make fun of Martha herself).

CHAOS (8pm, CBS) - The pilot episode of a new light drama about CIA spies who combat threats to national security. It stars Freddy Rodriguez ('Six Feet Under') and Eric Close ('Cold Case').

Who Do You Think You Are? (8pm, NBC) - Gwyneth Paltrow traces her roots, centering her investigation on her paternal grandfather. She also digs up info on her mother's (Blythe Danner) side and discovers an ancestral connection to the island of Barbados.

Camelot (10pm, Starz) - A new historical drama chronicling the storied Arthurian legend. In this first episode, King Uther dies, leaving young commoner Arthur (Jamie Campbell Bower) as heir to the throne of England, where he is championed by the wizard Merlin (Joseph Fiennes) but destined to tangle with his evil half sister, the sorceress Morgan (Eva Green). There's a second episode at 11pm in which Arthur meets Guinevere (Tamsin Egerton), the woman of his dreams. Meanwhile, Morgan and King Lot conspire to attack Camelot and take the throne. Read our review here. For another take on the Arthur/Merlin saga, there's ....

Merlin (10pm, Syfy) - This BBC fantasy series on the Authurian legends of Merlin is in its third season on Syfy. Tonight's episode is the first of a two-part story in which Arthur and Merlin are captured by a slave trader while trying to retrieve the Cup of Life, a magical goblet that can give the gift of immortality through magical means.

Blue Bloods (10pm, CBS) - Danny's wife is kidnapped to prevent him from testifying against a Peruvian drug lord who's on trial for a murder that Danny witnessed.

The Soup Awards (10pm, E!) - Joel McHale honors unintentionally funny people and moments in pop culture.

Medium (8pm, CBS) - Allison's dreams cause to suspiciously scrutinize the newfound success of her brother, played by her real life brother David Arquette. Also, Devalos' new campaign manager becomes interested in Bridgette's abilities.

Your OWN Show: Oprah's Search for the Next TV Star (9pm, OWN) - Ten hopefuls vie for a chance at their own talk show in this new reality competition show. In tonight's first episode, the finalists (selected by online voting) are introduced to Oprah and must produce talk show segments under the watchful eye of Dr. Phil. Carson Kressley and Nancy O'Dell are the hosts, and Mark Burnett ("Survivor" "Apprentice") is the executive producer. Someone will be eliminated each week till Oprah has a new employee.

Unlikely Animal Friends 2 (9pm, National Geographic Channel) - A look at surprising animal friendships between rival species. Included: a lion, a tiger and a bear live together in perfect harmony at a wildlife rehabilitation center near Atlanta.

Merlin (10pm, Syfy) - In the first part of a two-part Season 3 premiere, Arthur and Merlin discover the long-missing Morgana and return her to Camelot. Shortly after her return, Uther's mind begins to fray and Merlin suspects  it's due to someone's magic and puts himself in danger investigating the source.

Friday Night Lights (8pm, NBC) - Coach Taylor realizes his East Dillon squad has problems both on and off the field. Also, Luke's injury worsens and Riggins makes a life decision that could backfire.

Whale Wars (9pm, Animal Planet) - It hasn't been a great week for whales, so it's comforting to know someone out there is fighting for them. In tonight's installment, the Sea Shepherds use their stealth boat the Ady Gil to ambush a Japanese reconnaissance vessel. Get 'em!

Merlin (10pm, Syfy) - In an effort to end Uther's reign, the sorcerer Morgause revives the formidable Knights of Medhir and convinces her half sister Morgana to cast a sleeping spell on the people of Camelot.

Miami  Medical (10pm, CBS) - A construction worker becomes trapped underground when a giant sinkhole opens, and Serena has an unexpected encounter with Dr. Kaye.

There are also a ton of Michael Jackson programs on tonight, marking the first anniversary of his death, including special editions of "20/20" and "Dateline." Read the full schedule here.

Merlin (8pm, NBC) - Merlin is saved from a magical winged creature by young Lancelot (Santiago Cabrera), and then tries to help Lancelot become a knight in King Arthur's court.

Army Wives (10pm, Lifetime) - Chase comes home early but has difficulty readjusting, and Joan decideds to christen her baby before she's deployed.

Iron Chef America (10pm, Food) - A showdown between New York Chef Sue Torres and Iron Chef Bobby Flay. Judges are Isaac Mizrahi, Mark Bittman, and Isabel Gonzalez.

Merlin (8pm, NBC) - NBC didn't score with their futuristic retelling of David & Goliath, but maybe there's magic in "Merlin," a fantasy show about the pre-Camelot years of Arthur. Stars Anthony Head (left), who played Giles on "Buffy the Vampire Slayer." Back-to-back episodes at 8 and 9.

Impact (9pm, ABC) - Part one of a two-part sci-fi movie about the moon on a collision course with the earth. Starring James Cromwell and Steven Culp.

True Blood (9pm, HBO) - Sookie goes too far in helping Jessica adjust to her new life, and Jason makes an enemy at the Light of Day leadership conference.

In Plain Sight (10pm, USA) - Mary's sister Brandi is charged with drug trafficking and murder.