Question: Which television personality is most famous for appearing on a History channel series about evidence of past human-extraterrestrial contact?

Context articles: History Rocks
UFO Hunters
Digging for the Truth
Richard Benjamin Harrison
Ancient Aliens
Caltrans District 7 Headquarters
Steven M. Gillon
Giorgio A. Tsoukalos
David W. Zucker
Shootout!

History Rocks was a non-fictional, educational television program shown on The History Channel.
 Each episode explains eight historical events, arranged by decade, through multimedia presentations consisting of photographs, archival footage, popular music and pop-up trivia.
 Six episodes were produced, with two focusing on 1960s, 1970s and 1980s.
 At one time, the History Channel website discussed a fourth special on the topic of Sex, but the official "History Rocks"' website at the History Channel no longer mentions it.
UFO Hunters is an American television series that premiered on January 30, 2008 on The History Channel, produced by Motion Picture Production Inc., and ran for three seasons.
 Jon Alon Walz was the Executive Producer of the show and was responsible for selling the series to History Channel after a bidding war for the rights to the show broke out between History Channel and Sci-Fi Channel (now Syfy).
Digging for the Truth is a History Channel television series.
 The first three seasons of the show focused on host Josh Bernstein, who journeyed on various explorations of historical icons and mysteries.
 Bernstein is the president and CEO of BOSS (Boulder Outdoor Survival School) and has a degree in anthropology and psychology from Cornell University.
 The show airs every Monday night at 9:00 EST on the History Channel.
 The series premiered in January 2005 and has since become the highest-rated series in the history of The History Channel, which was surprising given the previous show "Time Titans" from the production crew never made it past the pilot.
 The third season premiered on January 22, 2007, with a two-hour special event on the quest for Atlantis.
Richard Benjamin Harrison Jr., (also known by the nicknames The Old Man and The Appraiser) (born March 4, 1941), is a Las Vegas businessman and reality television personality, best known as the co-owner of the World Famous Gold & Silver Pawn Shop, as featured on the History channel series "Pawn Stars".
 Harrison was the co-owner of a pawn shop with his son Rick Harrison until he suffered a stroke, causing him to retire.They opened the store together in 1989.
Ancient Aliens is an American television series that premiered on April 20, 2010, on the History channel.
 Produced by Prometheus Entertainment in a documentary style, the program presents hypotheses of ancient astronauts and proposes that historical texts, archaeology, and legends contain evidence of past human-extraterrestrial contact.
 The show has been criticized for presenting pseudoscience and pseudohistory.
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The Caltrans District 7 Headquarters building at 100 South Main Street in Downtown Los Angeles, California serves the California Department of Transportation (Caltrans) and the Los Angeles Department of Transportation.
 Built on a $165,000,000 budget it opened on September 24 2004.
 Its futuristic and environmentally friendly design has won its designer Thom Mayne the 2005 Pritzker Prize.
 The design and construction of the building was documented across four episodes on the History Channel series Modern Marvels, to demonstrate the unique challenges presented in the design and construction of large buildings over the past two centuries.
Steven M. Gillon is the resident historian of The History Channel and professor of Modern U.S. History at The University of Oklahoma.
 He received his Ph.D from Brown University.
 He has written numerous books and articles on modern American politics and culture.
 From 1998-2006, he anchored the History Channel's Sunday morning current events program "HistoryCENTER".
 In 2006-07 he hosted the History Channel series "Our Generation".
Giorgio A. Tsoukalos (Greek: Γεώργιος Α.
 Τσούκαλος ; born March 14, 1978) is a Greek-Swiss television personality.
 He is a proponent of the idea that ancient alien astronauts interacted with ancient humans.
 He is most famous for his appearances on the television series "Ancient Aliens".
David W. Zucker is President of Television for Scott Free, and Executive Producer of the landmark series adaptation of Philip K. Dick’s classic “The Man in the High Castle” for Amazon, esteemed Civil War medical drama “Mercy Street” on PBS, the forthcoming first season of the Amazon half-hour action-comedy starring Jean-Claude Van Damme as “Jean-Claude Van Johnson,” the AMC anthological psychological thriller “The Terror,” “The Good Fight," the widely acclaimed CBS all-access spin-off of “The Good Wife,” and “Killing Reagan,” the fourth in the acclaimed National Geographic channel series of “Killing” telefilms (which include “Killing Jesus” and “Killing Kennedy,” both Emmy-nominated, plus the docudrama “Killing Lincoln”).
 During his tenure, Scott Free has produced a steady stream of highly acclaimed programs including the Emmy and Golden Globe-nominated, Peabody-winning drama, “The Good Wife,” which recently concluded its 7th and final season on CBS, as well as “Numb3rs,” which ran for six successful seasons on the same network.
 Notable long form programs include “Klondike” for Discovery, the Emmy and Golden Globe-nominated “The Pillars of the Earth” for Starz, “World Without End” for Reelz, Emmy-nominated “Into the Storm” for HBO, Emmy-nominated “The Andromeda Strain” and “Coma” for A&E, the Golden Globe-nominated “The Company” at TNT and a feature-length digital series for X-Box/Microsoft, “Halo: Nightfall.”
 Acclaimed non-fiction programs include “Crimes of the Century” and the Emmy-winning documentary special “Gettysburg” for History Channel.
 Previously, Zucker worked as a Story Editor on the CBS series, Judging Amy, wrote pilot scripts for CBS and ABC, as well as various stage plays, and served as VP of Drama Series for CBS in addition to VP of Drama Series & Current Programs at Warner Bros.
 TV.
Shootout!
 was a documentary series featured on The History Channel and ran for two seasons from 2005 to 2006.
 It depicts actual firefights between United States military personnel and other combatants.
 There are also occasional episodes dedicated to police or S.W.A.T. team firefights, as well as Wild West shootouts.
 It also now has a feature of downloading and playing a first-person shooter, developed by Kuma Reality Games, detailing some of the battles.
 The battles include skirmishes from World War II, the Vietnam War, and the ongoing War on Terror in Afghanistan and during the 2003-2011 Iraq War.
 Season 1 was produced for The History Channel by Greystone Communications and Season 2 was produced by Flight 33 Productions.
 The series was created by Dolores Gavin (History Channel) and Louis Tarantino.