The complete 1918 Tarzan of the Apes.
First, before we discuss the first silver screen Tarzan, an admission must be made: there will never be better Tarzan movies than Tarzan the Ape Man and Tarzan and His Mate with Olympic swimmer Johnny Weissmuller. These classics of of the Golden Age of Hollywood, the first talkie Tarzans, are the archetypal Great White Hunter adventure stories, with everything anyone could ever want: love, pigmies, crocodiles, betrayal, 2-fisted action, huge guys in bad killer ape costumes, precipices, charged sexuality and an elephant stampede. Granted, they weren't even close to what Edgar Rice Burroughs wrote, but hey, who cares? These stand on their own right as honest-to-gosh competitors with 1925's The Lost World and the original King Kong as the best jungle adventure.
That said, 1918's Tarzan of the Apes is a very worthy first screen appearance of the wayward English lord. In fact, this is one of the only movie verions of the story which I can think of that is actually true to the story of the novel in its essentials.
As the film opens, we are introduced to Lord and Lady Greystroke, who are left abandoned on the African coast after a mutiny. Soon, they have their son John, but both are killed and John is taken into the protective custody of a tribe of apes. After seeing the young boy grow up, we are introduced to the adult Tarzan and he is introduced to white people for the first time. What follows are the trials of love with Jane and danger with Arab slavers.
The only major fault with the film is a fault with it's source material. Kudos to First National Films (the same people who produced The Lost World) for keeping it true to the book... The dowside being that the book doesn't lend itself well to a consistant film. Burroughs' novel is really "just a lot of stuff that happens". It's a great book, but it creates a disjointed film.
Elmo Lincoln plays the adult Tarzan, making a sort of strange and bulky Tarzan. Lincoln also gets the distinction of being the first screen Tarzan, but this isn't entirely true. First of all, the first Tarzan to appear on screen is actually the young Tarzan, played by Gordon Griffith. Secondly, Stellan Windrow was actually cast as the first Tarzan, and did 5 weeks of filming before he was called away to join the Navy in WWI. Lincoln's heavy set and fear of heights made it impossible to film the tree sequences with him, so he did the ground scenes while the leaner Windrow's footage was kept for the swinging. A careful eye will be able to note the difference.
The Disney weekday cartoon The Legend of Tarzan, picking up where their animated film left off, makes homage to this: in one episode, a Hollywood film crew has come to the jungle, and they've signed Tarzan to do the stunts in "Savage Man". They also joke on other film Tarzans when he recites his lines and observes "'me... savage...man...'... I don't talk like this!"
Tarzan of the Apes also shows a very unfortunate bit of datedness. There is a scene where Tarzan battles a lion to the death. The filming for this film took place long before the days of animal welfare, and this footage actually depicts Elmo Lincoln killing an older lion. If you're going to sit down with the family to watch this, I would not go so far as to tell the kids that bit of trivia.
Among the plethora of silent film Tarzans that followed, Lincoln starred in two direct sequels to Tarzan of the Apes, being Romance of Tarzan in 1918 and Adventures of Tarzan in 1920.