Nunca lo he conocido a él : Do I need to have the "lo"?

Direct objects moved to the start of a sentence require the redundant pronoun always: A él nunca lo he conocido.

When following the verb, the direct object has a redundant pronoun when -todo- is used: Ahora me lo tienes que contar todo.

Also required when it's necessary to reinforce a pronoun: La vi a ella pero no a él (not *vi a ella).

In other cases the redundant pronoun is generally avoided in Spain, but it's common in Lat.Am in spontaneous speech and in Argentina they even do it in literature: No lo conocen a Perón en Córdoba, lo confunden con un cantate de tangos. (In Spain, just "no conocen").

Not saying here that Spain is the model for "normal" Spanish because there's no such beast - and Spain weirdly departs from the "norm" in many other ways. What I am saying is that if you commit your sentence to paper (literature), then unless you're modelling Argentinos, it should be simply: Nunca he conocido a él.

Good luck!

edit: Very well. Whoever gave me thumbs down can read this. Full description in link below, but pertinent stuff copied here.

En el español general, el complemento directo tónico pospuesto al verbo no suele admitir la coaparición del pronombre átono, salvo que se trate también de un pronombre personal, caso en el que es obligada (→ 5.1). Solo es normal la duplicación en todo el ámbito hispánico cuando el complemento directo tónico es el pronombre todo: Lo sé todo; (Las) conozco a todas; cuando, con referente animado, el complemento directo es un numeral precedido de artículo: (Los) invité a los cuatro; o cuando se trata del indefinido uno y su referente es la persona que habla: Si la ven a una vacilar, enseguida se aprovechan. También favorecen la duplicación del complemento directo las oraciones de carácter enfático, como Ya lo creo que vendrá o ¡Vaya si las castigo a las niñas! La duplicación del complemento directo en otros casos (Lo vi a Juan; La saludé a María) es ajena a la norma culta de gran parte del ámbito hispánico, pero es normal en algunas regiones americanas, especialmente en los países del Río de la Plata: «Al pasar la madre cerca del baño la vio a Mariana tomando comprimidos» (Rausch/Bay Anorexia [Arg. 1990]).

Actually the "a él" is the optional part because the "lo" already refers to him.

Nunca lo he conocido. = I have never known/met him/it(masculine noun)

But by adding the "a él" signifies that you are referring to a PERSON and not a masculine object.

"lo" acts like those "me, te, le, nos, les" pronouns... except with the verb "conocer", you don't use "le", you use "lo". That's just a rule you must always remember that applies with some other verbs as well, just as "borrar" and "llamar"

Lo voy a borrar (a él) = I will delete him

Lo voy a llamar (a él) = I will call him

Whereas:

Voy a darle el regalo = I will give him the gift

Le voy a decir esto = I will tell him this.

It's a bit confusing, I know,... but you just have to remember some of those verbs.

I hope this helped! Espero haberte ayudado!

It shows you are talking Latin American Spanish. In Spain, it would have been "Nunca le he conocido."

It is the "a él" that is not necessary, being only there for emphasis, "He is the one whom I have never met."

In Brazilian Portuguese you could have said "Nunca conheci", relying on the context for "him" to have been guessed at.

I agree with Xenia and Laurence both are right (I have no idea whether Laurence's comment about Portuguese is right just because I don't speak Portuguese, but what they both wrote about Spanish is OK) So I have nothing to add to their comments but to offer you have a look on my video http://youtu.be/dWbZ1Wl1CV0 I put there some examples of the use of "le", "la" "los","se", etc.

yes you need the lo.

it sounds better.